diff --git a/src/main/java/com/google/devtools/build/lib/analysis/TransitiveInfoCollection.java b/src/main/java/com/google/devtools/build/lib/analysis/TransitiveInfoCollection.java
index 51cf588..1ba59847 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/TransitiveInfoCollection.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/TransitiveInfoCollection.java
@@ -24,10 +24,7 @@
 import com.google.devtools.build.lib.collect.nestedset.Order;
 import com.google.devtools.build.lib.packages.RequiredProviders;
 import com.google.devtools.build.lib.skyframe.BuildConfigurationValue;
-import com.google.devtools.build.lib.skylarkinterface.Param;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkbuildapi.TransitiveInfoCollectionApi;
 import com.google.devtools.build.lib.syntax.SkylarkIndexable;
 import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
 import javax.annotation.Nullable;
@@ -47,37 +44,10 @@
  * @see com.google.devtools.build.lib.analysis.RuleConfiguredTargetFactory
  * @see TransitiveInfoProvider
  */
-@SkylarkModule(
-  name = "Target",
-  category = SkylarkModuleCategory.BUILTIN,
-  doc =
-      "A BUILD target. It is essentially a <code>struct</code> with the following fields:"
-          + "<ul>"
-          + "<li><h3 id=\"modules.Target.label\">label</h3><code><a class=\"anchor\" "
-          + "href=\"Label.html\">Label</a> Target.label</code><br>The identifier of the "
-          + "target.</li>"
-          + "<li><h3 id=\"modules.Target.files\">files</h3><code><a class=\"anchor\" "
-          + "href=\"depset.html\">depset</a> Target.files </code><br>The set of "
-          + "<a class=\"anchor\" href=\"File.html\">File</a>s produced directly by this "
-          + "target.</li>"
-          + "<li><h3 id=\"modules.Target.aspect_ids\">aspect_ids</h3><code><a class=\"anchor\""
-          + "href=\"list.html\">list</a> Target.aspect_ids </code><br>The list of "
-          + "<a class=\"anchor\" href=\"ctx.html#aspect_id\">aspect_id</a>s applied to this "
-          + "target.</li>"
-          + "<li><h3 id=\"modules.Target.extraproviders\">Extra providers</h3>For rule targets all "
-          + "additional providers provided by this target are accessible as <code>struct</code> "
-          + "fields. These extra providers are defined in the <code>struct</code> returned by the "
-          + "rule implementation function.</li>"
-          + "</ul>"
-)
-public interface TransitiveInfoCollection extends SkylarkIndexable, SkylarkProviderCollection {
+public interface TransitiveInfoCollection
+    extends SkylarkIndexable, SkylarkProviderCollection, TransitiveInfoCollectionApi {
 
-  @SkylarkCallable(name = "output_group",
-    documented = false, //  TODO(dslomov): document.
-    parameters = {
-      @Param(name = "group_name", type = String.class, doc = "Output group name", named = true)
-    }
-  )
+  @Override
   default SkylarkNestedSet outputGroup(String group) {
     OutputGroupInfo provider = OutputGroupInfo.get(this);
     NestedSet<Artifact> result = provider != null
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
index afd1735..9364641 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
@@ -51,10 +51,9 @@
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.packages.TestTimeout;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkbuildapi.BuildConfigurationApi;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkInterfaceUtils;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
 import com.google.devtools.build.lib.util.OS;
 import com.google.devtools.build.lib.util.RegexFilter;
 import com.google.devtools.build.lib.vfs.Path;
@@ -102,18 +101,10 @@
  *
  * <pre>c1.equals(c2) <=> c1==c2.</pre>
  */
-@SkylarkModule(
-  name = "configuration",
-  category = SkylarkModuleCategory.BUILTIN,
-  doc =
-      "This object holds information about the environment in which the build is running. See "
-          + "the <a href='../rules.$DOC_EXT#configurations'>Rules page</a> for more on the general "
-          + "concept of configurations."
-)
 // TODO(janakr): If overhead of fragments class names is too high, add constructor that just takes
 // fragments and gets names from them.
 @AutoCodec
-public class BuildConfiguration {
+public class BuildConfiguration implements BuildConfigurationApi {
   /**
    * Sorts fragments by class name. This produces a stable order which, e.g., facilitates consistent
    * output from buildMnemonic.
@@ -1453,8 +1444,7 @@
   }
 
   /** Returns the bin directory for this build configuration. */
-  @SkylarkCallable(name = "bin_dir", structField = true, documented = false)
-  @Deprecated
+  @Override
   public ArtifactRoot getBinDirectory() {
     return getBinDirectory(RepositoryName.MAIN);
   }
@@ -1488,8 +1478,7 @@
   }
 
   /** Returns the genfiles directory for this build configuration. */
-  @SkylarkCallable(name = "genfiles_dir", structField = true, documented = false)
-  @Deprecated
+  @Override
   public ArtifactRoot getGenfilesDirectory() {
     return getGenfilesDirectory(RepositoryName.MAIN);
   }
@@ -1538,8 +1527,7 @@
    * not match the host platform. You should only use this when invoking tools that are known to use
    * the native path separator, i.e., the path separator for the machine that they run on.
    */
-  @SkylarkCallable(name = "host_path_separator", structField = true,
-      doc = "Returns the separator for PATH environment variable, which is ':' on Unix.")
+  @Override
   public String getHostPathSeparator() {
     // TODO(bazel-team): Maybe do this in the constructor instead? This isn't serialization-safe.
     return OS.getCurrent() == OS.WINDOWS ? ";" : ":";
@@ -1578,13 +1566,6 @@
     return actionEnv;
   }
 
-  @SkylarkCallable(
-    name = "default_shell_env",
-    structField = true,
-    doc =
-        "A dictionary representing the static local shell environment. It maps variables "
-            + "to their values (strings)."
-  )
   /**
    * Return the "fixed" part of the actions' environment variables.
    *
@@ -1596,7 +1577,7 @@
    * <p>Since values of the "fixed" variables are already known at analysis phase, it is returned
    * here as a map.
    */
-  @Deprecated // Use getActionEnvironment instead.
+  @Override
   public ImmutableMap<String, String> getLocalShellEnvironment() {
     return actionEnv.getFixedEnv();
   }
@@ -1749,14 +1730,7 @@
    * Returns user-specified test environment variables and their values, as set by the --test_env
    * options.
    */
-  @Deprecated
-  @SkylarkCallable(
-    name = "test_env",
-    structField = true,
-    doc =
-        "A dictionary containing user-specified test environment variables and their values, "
-            + "as set by the --test_env options. DO NOT USE! This is not the complete environment!"
-  )
+  @Override
   public ImmutableMap<String, String> getTestEnv() {
     return testEnv.getFixedEnv();
   }
@@ -1785,11 +1759,7 @@
     return options.deferParamFiles;
   }
 
-  @SkylarkCallable(name = "coverage_enabled", structField = true,
-      doc = "A boolean that tells whether code coverage is enabled for this run. Note that this "
-          + "does not compute whether a specific rule should be instrumented for code coverage "
-          + "data collection. For that, see the <a href=\"ctx.html#coverage_instrumented\"><code>"
-          + "ctx.coverage_instrumented</code></a> function.")
+  @Override
   public boolean isCodeCoverageEnabled() {
     return options.collectCodeCoverage;
   }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentCollection.java b/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentCollection.java
index bd053f4..d396bcc 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentCollection.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentCollection.java
@@ -18,26 +18,13 @@
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransition;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
-import com.google.devtools.build.lib.syntax.ClassObject;
+import com.google.devtools.build.lib.skylarkbuildapi.FragmentCollectionApi;
 import javax.annotation.Nullable;
 
-/**
- * Represents a collection of configuration fragments in Skylark.
- */
+/** Represents a collection of configuration fragments in Skylark. */
 // Documentation can be found at ctx.fragments
 @Immutable
-@SkylarkModule(name = "fragments",
-    category = SkylarkModuleCategory.NONE,
-    doc = "Possible fields are "
-    + "<a href=\"apple.html\">apple</a>, <a href=\"cpp.html\">cpp</a>, "
-    + "<a href=\"java.html\">java</a>, <a href=\"jvm.html\">jvm</a> and "
-    + "<a href=\"objc.html\">objc</a>, <a href=\"android.html\">android</a>. "
-    + "Access a specific fragment by its field name ex:</p><code>ctx.fragments.apple</code></p>"
-    + "Note that rules have to declare their required fragments in order to access them "
-    + "(see <a href=\"../rules.md#fragments\">here</a>).")
-public class FragmentCollection implements ClassObject {
+public class FragmentCollection implements FragmentCollectionApi {
   private final RuleContext ruleContext;
   private final ConfigurationTransition transition;
 
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttributesCollection.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttributesCollection.java
index 6821129..ae13ebf 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttributesCollection.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttributesCollection.java
@@ -24,11 +24,8 @@
 import com.google.devtools.build.lib.packages.BuildType;
 import com.google.devtools.build.lib.packages.Info;
 import com.google.devtools.build.lib.packages.NativeProvider;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkbuildapi.SkylarkAttributesCollectionApi;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.syntax.Environment;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.Runtime;
@@ -41,12 +38,8 @@
 import java.util.List;
 import java.util.Map;
 
-@SkylarkModule(
-  name = "rule_attributes",
-  category = SkylarkModuleCategory.NONE,
-  doc = "Information about attributes of a rule an aspect is applied to."
-)
-class SkylarkAttributesCollection implements SkylarkValue {
+/** Information about attributes of a rule an aspect is applied to. */
+class SkylarkAttributesCollection implements SkylarkAttributesCollectionApi {
   private final SkylarkRuleContext skylarkRuleContext;
   private final Info attrObject;
   private final Info executableObject;
@@ -91,35 +84,31 @@
     skylarkRuleContext.checkMutable("rule." + attrName);
   }
 
-  @SkylarkCallable(name = "attr", structField = true, doc = SkylarkRuleContext.ATTR_DOC)
+  @Override
   public Info getAttr() throws EvalException {
     checkMutable("attr");
     return attrObject;
   }
 
-  @SkylarkCallable(name = "executable", structField = true, doc = SkylarkRuleContext.EXECUTABLE_DOC)
+  @Override
   public Info getExecutable() throws EvalException {
     checkMutable("executable");
     return executableObject;
   }
 
-  @SkylarkCallable(name = "file", structField = true, doc = SkylarkRuleContext.FILE_DOC)
+  @Override
   public Info getFile() throws EvalException {
     checkMutable("file");
     return fileObject;
   }
 
-  @SkylarkCallable(name = "files", structField = true, doc = SkylarkRuleContext.FILES_DOC)
+  @Override
   public Info getFiles() throws EvalException {
     checkMutable("files");
     return filesObject;
   }
 
-  @SkylarkCallable(
-    name = "kind",
-    structField = true,
-    doc = "The kind of a rule, such as 'cc_library'"
-  )
+  @Override
   public String getRuleClassName() throws EvalException {
     checkMutable("kind");
     return ruleClassName;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
index 0614e1e..75e4f63 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
@@ -13,7 +13,7 @@
 // limitations under the License.
 
 package com.google.devtools.build.lib.analysis.skylark;
-
+  
 import com.google.common.base.Function;
 import com.google.common.base.Optional;
 import com.google.common.base.Preconditions;
@@ -43,7 +43,6 @@
 import com.google.devtools.build.lib.analysis.config.FragmentCollection;
 import com.google.devtools.build.lib.analysis.config.HostTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.NoTransition;
-import com.google.devtools.build.lib.analysis.configuredtargets.AbstractConfiguredTarget;
 import com.google.devtools.build.lib.analysis.configuredtargets.RuleConfiguredTarget.Mode;
 import com.google.devtools.build.lib.analysis.stringtemplate.ExpansionException;
 import com.google.devtools.build.lib.analysis.test.InstrumentedFilesCollector;
@@ -64,11 +63,9 @@
 import com.google.devtools.build.lib.packages.RawAttributeMapper;
 import com.google.devtools.build.lib.shell.ShellUtils;
 import com.google.devtools.build.lib.shell.ShellUtils.TokenizationException;
-import com.google.devtools.build.lib.skylarkinterface.Param;
-import com.google.devtools.build.lib.skylarkinterface.ParamType;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkbuildapi.FileApi;
+import com.google.devtools.build.lib.skylarkbuildapi.FileRootApi;
+import com.google.devtools.build.lib.skylarkbuildapi.SkylarkRuleContextApi;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.syntax.ClassObject;
@@ -99,108 +96,17 @@
 import java.util.Set;
 import javax.annotation.Nullable;
 
-/** A Skylark API for the ruleContext.
+/**
+ * A Skylark API for the ruleContext.
  *
- * "This object becomes featureless once the rule implementation function that it was created for
+ * <p>"This object becomes featureless once the rule implementation function that it was created for
  * has completed. To achieve this, the {@link #nullify()} should be called once the evaluation of
  * the function is completed. The method both frees memory by deleting all significant fields of the
  * object and makes it impossible to accidentally use this object where it's not supposed to be used
  * (such attempts will result in {@link EvalException}s).
  */
-@SkylarkModule(
-  name = "ctx",
-  category = SkylarkModuleCategory.BUILTIN,
-  doc =
-      "The context of the rule containing helper functions and "
-          + "information about attributes, depending targets and outputs. "
-          + "You get a ctx object as an argument to the <code>implementation</code> function when "
-          + "you create a rule."
-)
-public final class SkylarkRuleContext implements SkylarkValue {
+public final class SkylarkRuleContext implements SkylarkRuleContextApi {
 
-  private static final String DOC_NEW_FILE_TAIL = "Does not actually create a file on the file "
-      + "system, just declares that some action will do so. You must create an action that "
-      + "generates the file. If the file should be visible to other rules, declare a rule output "
-      + "instead when possible. Doing so enables Blaze to associate a label with the file that "
-      + "rules can refer to (allowing finer dependency control) instead of referencing the whole "
-      + "rule.";
-  public static final String EXECUTABLE_DOC =
-      "A <code>struct</code> containing executable files defined in label type "
-          + "attributes marked as <code>executable=True</code>. The struct fields correspond "
-          + "to the attribute names. Each value in the struct is either a <code>file</code> or "
-          + "<code>None</code>. If an optional attribute is not specified in the rule "
-          + "then the corresponding struct value is <code>None</code>. If a label type is not "
-          + "marked as <code>executable=True</code>, no corresponding struct field is generated. "
-          + "<a href=\"https://github.com/bazelbuild/examples/blob/master/rules/actions_run/"
-          + "execute.bzl\">See example of use</a>.";
-  public static final String FILES_DOC =
-      "A <code>struct</code> containing files defined in label or label list "
-          + "type attributes. The struct fields correspond to the attribute names. The struct "
-          + "values are <code>list</code> of <code>file</code>s.  "
-          + "It is a shortcut for:"
-          + "<pre class=language-python>[f for t in ctx.attr.&lt;ATTR&gt; for f in t.files]</pre> "
-          + "In other words, use <code>files</code> to access the "
-          + "<a href=\"../rules.$DOC_EXT#requesting-output-files\">default outputs</a> of a "
-          + "dependency. "
-          + "<a href=\"https://github.com/bazelbuild/examples/blob/master/rules/depsets/foo.bzl\">"
-          + "See example of use</a>.";
-  public static final String FILE_DOC =
-      "A <code>struct</code> containing files defined in label type "
-          + "attributes marked as <code>allow_single_file</code>. The struct fields correspond "
-          + "to the attribute names. The struct value is always a <code>file</code> or "
-          + "<code>None</code>. If an optional attribute is not specified in the rule "
-          + "then the corresponding struct value is <code>None</code>. If a label type is not "
-          + "marked as <code>allow_single_file</code>, no corresponding struct field is generated. "
-          + "It is a shortcut for:"
-          + "<pre class=language-python>list(ctx.attr.&lt;ATTR&gt;.files)[0]</pre>"
-          + "In other words, use <code>file</code> to access the (singular) "
-          + "<a href=\"../rules.$DOC_EXT#requesting-output-files\">default output</a> of a "
-          + "dependency. "
-          + "<a href=\"https://github.com/bazelbuild/examples/blob/master/rules/expand_template/"
-          + "hello.bzl\">See example of use</a>.";
-  public static final String ATTR_DOC =
-      "A struct to access the values of the attributes. The values are provided by "
-          + "the user (if not, a default value is used). The attributes of the struct and the "
-          + "types of their values correspond to the keys and values of the <code>attrs</code> "
-          + "dict provided to the <code>rule</code> function. "
-          + "<a href=\"https://github.com/bazelbuild/examples/blob/master/rules/attributes/"
-          + "printer.bzl\">See example of use</a>.";
-  public static final String SPLIT_ATTR_DOC =
-      "A struct to access the values of attributes with split configurations. If the attribute is "
-          + "a label list, the value of split_attr is a dict of the keys of the split (as strings) "
-          + "to lists of the ConfiguredTargets in that branch of the split. If the attribute is a "
-          + "label, then the value of split_attr is a dict of the keys of the split (as strings) "
-          + "to single ConfiguredTargets. Attributes with split configurations still appear in the "
-          + "attr struct, but their values will be single lists with all the branches of the split "
-          + "merged together.";
-  public static final String OUTPUTS_DOC =
-      "A pseudo-struct containing all the predeclared output files, represented by "
-          + "<a href='File.html'><code>File</code></a> objects. See the "
-          + "<a href='../rules.$DOC_EXT#files'>Rules page</a> for more information and examples."
-          + "<p>This field does not exist on aspect contexts, since aspects do not have "
-          + "predeclared outputs."
-          + "<p>The fields of this object are defined as follows. It is an error if two outputs "
-          + "produce the same field name or have the same label."
-          + "<ul>"
-          + "<li>If the rule declares an <a href='globals.html#rule.outputs'><code>outputs</code>"
-          + "</a> dict, then for every entry in the dict, there is a field whose name is the key "
-          + "and whose value is the corresponding <code>File</code>."
-          + "<li>For every attribute of type <a href='attr.html#output'><code>attr.output</code>"
-          + "</a> that the rule declares, there is a field whose name is the attribute's name. "
-          + "If the target specified a label for that attribute, then the field value is the "
-          + "corresponding <code>File</code>; otherwise the field value is <code>None</code>."
-          + "<li>For every attribute of type <a href='attr.html#output_list'><code>attr.output_list"
-          + "</code></a> that the rule declares, there is a field whose name is the attribute's "
-          + "name. The field value is a list of <code>File</code> objects corresponding to the "
-          + "labels given for that attribute in the target, or an empty list if the attribute was "
-          + "not specified in the target."
-          + "<li><b>(Deprecated)</b> If the rule is marked <a href='globals.html#rule.executable'>"
-          + "<code>executable</code></a> or <a href='globals.html#rule.test'><code>test</code></a>,"
-          + "there is a field named <code>\"executable\"</code>, which is the default executable. "
-          + "It is recommended that instead of using this, you pass another file (either "
-          + "predeclared or not) to the <code>executable</code> arg of "
-          + "<a href='globals.html#DefaultInfo'><code>DefaultInfo</code></a>."
-          + "</ul>";
   public static final Function<Attribute, Object> ATTRIBUTE_VALUE_EXTRACTOR_FOR_ASPECT =
       new Function<Attribute, Object>() {
         @Nullable
@@ -573,34 +479,17 @@
     return ruleContext;
   }
 
-  @SkylarkCallable(
-    name = "default_provider",
-    structField = true,
-    doc = "Deprecated. Use <a href=\"globals.html#DefaultInfo\">DefaultInfo</a> instead."
-  )
-  public static Provider getDefaultProvider() {
+  @Override
+  public Provider getDefaultProvider() {
     return DefaultInfo.PROVIDER;
   }
 
-  @SkylarkCallable(
-      name = "actions",
-      structField = true,
-      doc = "Functions to declare files and create actions."
-  )
+  @Override
   public SkylarkActionFactory actions() {
     return actionFactory;
   }
 
-  @SkylarkCallable(name = "created_actions",
-      doc = "For rules with <a href=\"globals.html#rule._skylark_testable\">_skylark_testable"
-          + "</a> set to <code>True</code>, this returns an "
-          + "<a href=\"globals.html#Actions\">Actions</a> provider representing all actions "
-          + "created so far for the current rule. For all other rules, returns <code>None</code>. "
-          + "Note that the provider is not updated when subsequent actions are created, so you "
-          + "will have to call this function again if you wish to inspect them. "
-          + "<br/><br/>"
-          + "This is intended to help write tests for rule-implementation helper functions, which "
-          + "may take in a <code>ctx</code> object and create actions on it.")
+  @Override
   public SkylarkValue createdActions() throws EvalException {
     checkMutable("created_actions");
     if (ruleContext.getRule().getRuleClassObject().isSkylarkTestable()) {
@@ -611,13 +500,13 @@
     }
   }
 
-  @SkylarkCallable(name = "attr", structField = true, doc = ATTR_DOC)
+  @Override
   public Info getAttr() throws EvalException {
     checkMutable("attr");
     return attributesCollection.getAttr();
   }
 
-  @SkylarkCallable(name = "split_attr", structField = true, doc = SPLIT_ATTR_DOC)
+  @Override
   public Info getSplitAttr() throws EvalException {
     checkMutable("split_attr");
     if (splitAttributes == null) {
@@ -628,88 +517,63 @@
   }
 
   /** See {@link RuleContext#getExecutablePrerequisite(String, Mode)}. */
-  @SkylarkCallable(name = "executable", structField = true, doc = EXECUTABLE_DOC)
+  @Override
   public Info getExecutable() throws EvalException {
     checkMutable("executable");
     return attributesCollection.getExecutable();
   }
 
   /** See {@link RuleContext#getPrerequisiteArtifact(String, Mode)}. */
-  @SkylarkCallable(name = "file", structField = true, doc = FILE_DOC)
+  @Override
   public Info getFile() throws EvalException {
     checkMutable("file");
     return attributesCollection.getFile();
   }
 
   /** See {@link RuleContext#getPrerequisiteArtifacts(String, Mode)}. */
-  @SkylarkCallable(name = "files", structField = true, doc = FILES_DOC)
+  @Override
   public Info getFiles() throws EvalException {
     checkMutable("files");
     return attributesCollection.getFiles();
   }
 
-  @SkylarkCallable(name = "workspace_name", structField = true,
-      doc = "Returns the workspace name as defined in the WORKSPACE file.")
+  @Override
   public String getWorkspaceName() throws EvalException {
     checkMutable("workspace_name");
     return ruleContext.getWorkspaceName();
   }
 
-  @SkylarkCallable(name = "label", structField = true, doc = "The label of this rule.")
+  @Override
   public Label getLabel() throws EvalException {
     checkMutable("label");
     return ruleContext.getLabel();
   }
 
-  @SkylarkCallable(name = "fragments", structField = true,
-      doc = "Allows access to configuration fragments in target configuration.")
+  @Override
   public FragmentCollection getFragments() throws EvalException {
     checkMutable("fragments");
     return fragments;
   }
 
-  @SkylarkCallable(name = "host_fragments", structField = true,
-      doc = "Allows access to configuration fragments in host configuration.")
+  @Override
   public FragmentCollection getHostFragments() throws EvalException {
     checkMutable("host_fragments");
     return hostFragments;
   }
 
-  @SkylarkCallable(name = "configuration", structField = true,
-      doc = "Returns the default configuration. See the <a href=\"configuration.html\">"
-          + "configuration</a> type for more details.")
+  @Override
   public BuildConfiguration getConfiguration() throws EvalException {
     checkMutable("configuration");
     return ruleContext.getConfiguration();
   }
 
-  @SkylarkCallable(name = "host_configuration", structField = true,
-      doc = "Returns the host configuration. See the <a href=\"configuration.html\">"
-          + "configuration</a> type for more details.")
+  @Override
   public BuildConfiguration getHostConfiguration() throws EvalException {
     checkMutable("host_configuration");
     return ruleContext.getHostConfiguration();
   }
 
-  @SkylarkCallable(name = "coverage_instrumented",
-    doc = "Returns whether code coverage instrumentation should be generated when performing "
-        + "compilation actions for this rule or, if <code>target</code> is provided, the rule "
-        + "specified by that Target. (If a non-rule or a Skylark rule Target is provided, this "
-        + "returns False.) Checks if the sources of the current rule (if no Target is provided) or"
-        + "the sources of Target should be instrumented based on the --instrumentation_filter and"
-        + "--instrument_test_targets config settings. "
-        + "This differs from <code>coverage_enabled</code> in the <a href=\"configuration.html\">"
-        + "configuration</a>, which notes whether coverage data collection is enabled for the "
-        + "entire run, but not whether a specific target should be instrumented.",
-    parameters = {
-      @Param(
-          name = "target",
-          type = TransitiveInfoCollection.class,
-          defaultValue = "None",
-          noneable = true,
-          named = true,
-          doc = "A Target specifying a rule. If not provided, defaults to the current rule.")
-    })
+  @Override
   public boolean instrumentCoverage(Object targetUnchecked) throws EvalException {
     checkMutable("coverage_instrumented");
     BuildConfiguration config = ruleContext.getConfiguration();
@@ -724,35 +588,25 @@
         && InstrumentedFilesCollector.shouldIncludeLocalSources(config, target);
   }
 
-  @SkylarkCallable(name = "features", structField = true,
-      doc = "Returns the set of features that are enabled for this rule."
-  )
+  @Override
   public ImmutableList<String> getFeatures() throws EvalException {
     checkMutable("features");
     return ImmutableList.copyOf(ruleContext.getFeatures());
   }
 
-  @SkylarkCallable(
-    name = "bin_dir",
-    structField = true,
-    doc = "The root corresponding to bin directory."
-  )
+  @Override
   public ArtifactRoot getBinDirectory() throws EvalException {
     checkMutable("bin_dir");
     return getConfiguration().getBinDirectory(ruleContext.getRule().getRepository());
   }
 
-  @SkylarkCallable(
-    name = "genfiles_dir",
-    structField = true,
-    doc = "The root corresponding to genfiles directory."
-  )
+  @Override
   public ArtifactRoot getGenfilesDirectory() throws EvalException {
     checkMutable("genfiles_dir");
     return getConfiguration().getGenfilesDirectory(ruleContext.getRule().getRepository());
   }
 
-  @SkylarkCallable(structField = true, doc = OUTPUTS_DOC)
+  @Override
   public ClassObject outputs() throws EvalException {
     checkMutable("outputs");
     if (outputsObject == null) {
@@ -761,12 +615,7 @@
     return outputsObject;
   }
 
-  @SkylarkCallable(
-    structField = true,
-    doc =
-        "Returns rule attributes descriptor for the rule that aspect is applied to."
-            + " Only available in aspect implementation functions."
-  )
+  @Override
   public SkylarkAttributesCollection rule() throws EvalException {
     checkMutable("rule");
     if (!isForAspect) {
@@ -776,10 +625,7 @@
     return ruleAttributesCollection;
   }
 
-  @SkylarkCallable(structField = true,
-      name = "aspect_ids",
-      doc = "Returns a list ids for all aspects applied to the target."
-      + " Only available in aspect implementation functions.")
+  @Override
   public ImmutableList<String> aspectIds() throws EvalException {
     checkMutable("aspect_ids");
     if (!isForAspect) {
@@ -794,16 +640,13 @@
     return result.build();
   }
 
-  @SkylarkCallable(
-    structField = true,
-    doc = "Dictionary (String to String) of configuration variables."
-  )
+  @Override
   public SkylarkDict<String, String> var() throws EvalException {
     checkMutable("var");
     return makeVariables;
   }
 
-  @SkylarkCallable(structField = true, doc = "Toolchains required for this rule.")
+  @Override
   public SkylarkIndexable toolchains() throws EvalException {
     checkMutable("toolchains");
     return ruleContext.getToolchainContext().getResolvedToolchainProviders();
@@ -814,7 +657,7 @@
     return ruleLabelCanonicalName;
   }
 
-  @SkylarkCallable(doc = "Splits a shell command to a list of tokens.", documented = false)
+  @Override
   public SkylarkList<String> tokenize(String optionString) throws FuncallException, EvalException {
     checkMutable("tokenize");
     List<String> options = new ArrayList<>();
@@ -826,13 +669,7 @@
     return SkylarkList.createImmutable(options);
   }
 
-  @SkylarkCallable(
-    doc =
-        "Expands all references to labels embedded within a string for all files using a mapping "
-          + "from definition labels (i.e. the label in the output type attribute) to files. "
-          + "Deprecated.",
-    documented = false
-  )
+  @Override
   public String expand(
       @Nullable String expression, SkylarkList<Object> artifacts, Label labelResolver)
       throws EvalException, FuncallException {
@@ -852,20 +689,7 @@
     return isForAspect;
   }
 
-  @SkylarkCallable(
-    name = "new_file",
-    doc =
-        "DEPRECATED. Use <a href=\"actions.html#declare_file\">ctx.actions.declare_file</a>. <br>"
-            + "Creates a file object with the given filename, in the current package. "
-            + DOC_NEW_FILE_TAIL,
-    parameters = {
-      @Param(
-        name = "filename",
-        type = String.class,
-        doc = "The path of the new file, relative to the current package."
-      )
-    }
-  )
+  @Override
   public Artifact newFile(String filename) throws EvalException {
     checkDeprecated("ctx.actions.declare_file", "ctx.new_file", null, skylarkSemantics);
     checkMutable("new_file");
@@ -873,60 +697,30 @@
   }
 
   // Kept for compatibility with old code.
-  @SkylarkCallable(documented = false)
-  public Artifact newFile(ArtifactRoot root, String filename) throws EvalException {
+  @Override
+  public Artifact newFile(FileRootApi root, String filename) throws EvalException {
     checkMutable("new_file");
-    return ruleContext.getPackageRelativeArtifact(filename, root);
+    return ruleContext.getPackageRelativeArtifact(filename, (ArtifactRoot) root);
   }
 
-  @SkylarkCallable(
-      name = "new_file",
-      doc =
-          "Creates a new file object in the same directory as the original file. "
-              + DOC_NEW_FILE_TAIL,
-      parameters = {
-        @Param(
-          name = "sibling_file",
-          type = Artifact.class,
-          doc = "A file that lives in the same directory as the newly created file."
-        ),
-        @Param(
-          name = "basename",
-          type = String.class,
-          doc = "The base name of the newly created file."
-        )
-      }
-    )
-  public Artifact newFile(Artifact baseArtifact, String newBaseName) throws EvalException {
+  @Override
+  public Artifact newFile(FileApi baseArtifact, String newBaseName) throws EvalException {
     checkDeprecated("ctx.actions.declare_file", "ctx.new_file", null, skylarkSemantics);
     checkMutable("new_file");
     return actionFactory.declareFile(newBaseName, baseArtifact);
   }
 
   // Kept for compatibility with old code.
-  @SkylarkCallable(documented = false)
-  public Artifact newFile(ArtifactRoot root, Artifact baseArtifact, String suffix)
+  @Override
+  public Artifact newFile(FileRootApi root, FileApi baseArtifact, String suffix)
       throws EvalException {
     checkMutable("new_file");
-    PathFragment original = baseArtifact.getRootRelativePath();
+    PathFragment original = ((Artifact) baseArtifact).getRootRelativePath();
     PathFragment fragment = original.replaceName(original.getBaseName() + suffix);
-    return ruleContext.getDerivedArtifact(fragment, root);
+    return ruleContext.getDerivedArtifact(fragment, (ArtifactRoot) root);
   }
 
-  @SkylarkCallable(
-    name = "experimental_new_directory",
-    documented = false,
-    parameters = {
-      @Param(name = "name", type = String.class),
-      @Param(
-        name = "sibling",
-        type = Artifact.class,
-        defaultValue = "None",
-        noneable = true,
-        named = true
-      )
-    }
-  )
+  @Override
   public Artifact newDirectory(String name, Object siblingArtifactUnchecked) throws EvalException {
     checkDeprecated(
         "ctx.actions.declare_directory", "ctx.experimental_new_directory", null, skylarkSemantics);
@@ -934,7 +728,7 @@
     return actionFactory.declareDirectory(name, siblingArtifactUnchecked);
   }
 
-  @SkylarkCallable(documented = false)
+  @Override
   public boolean checkPlaceholders(String template, SkylarkList<Object> allowedPlaceholders)
       throws EvalException {
     checkMutable("check_placeholders");
@@ -950,26 +744,10 @@
     return true;
   }
 
-  @SkylarkCallable(doc =
-        "<b>Deprecated.</b> Use <code>ctx.var</code> to access the variables instead.<br>"
-      + "Returns a string after expanding all references to \"Make variables\". The variables "
-      + "must have the following format: <code>$(VAR_NAME)</code>. Also, <code>$$VAR_NAME"
-      + "</code> expands to <code>$VAR_NAME</code>. Parameters:"
-      + "<ul><li>The name of the attribute (<code>string</code>). It's only used for error "
-      + "reporting.</li>\n"
-      + "<li>The expression to expand (<code>string</code>). It can contain references to "
-      + "\"Make variables\".</li>\n"
-      + "<li>A mapping of additional substitutions (<code>dict</code> of <code>string</code> : "
-      + "<code>string</code>).</li></ul>\n"
-      + "Examples:"
-      + "<pre class=language-python>\n"
-      + "ctx.expand_make_variables(\"cmd\", \"$(MY_VAR)\", {\"MY_VAR\": \"Hi\"})  # == \"Hi\"\n"
-      + "ctx.expand_make_variables(\"cmd\", \"$$PWD\", {})  # == \"$PWD\"\n"
-      + "</pre>"
-      + "Additional variables may come from other places, such as configurations. Note that "
-      + "this function is experimental.")
-  public String expandMakeVariables(String attributeName, String command,
-      final Map<String, String> additionalSubstitutions) throws EvalException {
+  @Override
+  public String expandMakeVariables(
+      String attributeName, String command, final Map<String, String> additionalSubstitutions)
+      throws EvalException {
     checkMutable("expand_make_variables");
     ConfigurationMakeVariableContext makeVariableContext =
         new ConfigurationMakeVariableContext(
@@ -995,38 +773,19 @@
     return attributesCollection.getExecutableRunfilesMap().get(executable);
   }
 
-  @SkylarkCallable(
-    name = "info_file",
-    structField = true,
-    documented = false,
-    doc =
-        "Returns the file that is used to hold the non-volatile workspace status for the "
-            + "current build request."
-  )
+  @Override
   public Artifact getStableWorkspaceStatus() throws InterruptedException, EvalException {
     checkMutable("info_file");
     return ruleContext.getAnalysisEnvironment().getStableWorkspaceStatusArtifact();
   }
 
-  @SkylarkCallable(
-    name = "version_file",
-    structField = true,
-    documented = false,
-    doc =
-        "Returns the file that is used to hold the volatile workspace status for the "
-            + "current build request."
-  )
+  @Override
   public Artifact getVolatileWorkspaceStatus() throws InterruptedException, EvalException {
     checkMutable("version_file");
     return ruleContext.getAnalysisEnvironment().getVolatileWorkspaceStatusArtifact();
   }
 
-  @SkylarkCallable(
-    name = "build_file_path",
-    structField = true,
-    documented = true,
-    doc = "Returns path to the BUILD file for this rule, relative to the source root."
-  )
+  @Override
   public String getBuildFileRelativePath() throws EvalException {
     checkMutable("build_file_path");
     Package pkg = ruleContext.getRule().getPackage();
@@ -1039,161 +798,7 @@
    * executable = executable, arguments = [argument1, argument2, ...], mnemonic = 'Mnemonic',
    * command = 'command', )
    */
-  @SkylarkCallable(
-    name = "action",
-    doc =
-        "DEPRECATED. Use <a href=\"actions.html#run\">ctx.actions.run()</a> or"
-            + " <a href=\"actions.html#run_shell\">ctx.actions.run_shell()</a>. <br>"
-            + "Creates an action that runs an executable or a shell command."
-            + " You must specify either <code>command</code> or <code>executable</code>.\n"
-            + "Actions and genrules are very similar, but have different use cases. Actions are "
-            + "used inside rules, and genrules are used inside macros. Genrules also have make "
-            + "variable expansion.",
-    parameters = {
-      @Param(
-        name = "outputs",
-        type = SkylarkList.class,
-        generic1 = Artifact.class,
-        named = true,
-        positional = false,
-        doc = "List of the output files of the action."
-      ),
-      @Param(
-        name = "inputs",
-        allowedTypes = {
-          @ParamType(type = SkylarkList.class),
-          @ParamType(type = SkylarkNestedSet.class),
-        },
-        generic1 = Artifact.class,
-        defaultValue = "[]",
-        named = true,
-        positional = false,
-        doc = "List of the input files of the action."
-      ),
-      @Param(
-        name = "executable",
-        type = Object.class,
-        allowedTypes = {
-          @ParamType(type = Artifact.class),
-          @ParamType(type = String.class),
-          @ParamType(type = Runtime.NoneType.class),
-        },
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        positional = false,
-        doc = "The executable file to be called by the action."
-      ),
-      @Param(
-        name = "tools",
-        allowedTypes = {
-          @ParamType(type = SkylarkList.class),
-          @ParamType(type = SkylarkNestedSet.class),
-        },
-        generic1 = Artifact.class,
-        defaultValue = "unbound",
-        named = true,
-        positional = false,
-        doc =
-            "List of the any tools needed by the action. Tools are inputs with additional "
-                + "runfiles that are automatically made available to the action."
-      ),
-      @Param(
-        name = "arguments",
-        allowedTypes = {
-          @ParamType(type = SkylarkList.class),
-        },
-        defaultValue = "[]",
-        named = true,
-        positional = false,
-        doc =
-            "Command line arguments of the action."
-                + "Must be a list of strings or actions.args() objects."
-      ),
-      @Param(
-        name = "mnemonic",
-        type = String.class,
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        positional = false,
-        doc = "A one-word description of the action, e.g. CppCompile or GoLink."
-      ),
-      @Param(
-        name = "command",
-        type = Object.class,
-        allowedTypes = {
-          @ParamType(type = String.class),
-          @ParamType(type = SkylarkList.class, generic1 = String.class),
-          @ParamType(type = Runtime.NoneType.class),
-        },
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        positional = false,
-        doc =
-            "Shell command to execute. It is usually preferable to "
-                + "use <code>executable</code> instead. "
-                + "Arguments are available with <code>$1</code>, <code>$2</code>, etc."
-      ),
-      @Param(
-        name = "progress_message",
-        type = String.class,
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        positional = false,
-        doc =
-            "Progress message to show to the user during the build, "
-                + "e.g. \"Compiling foo.cc to create foo.o\"."
-      ),
-      @Param(
-        name = "use_default_shell_env",
-        type = Boolean.class,
-        defaultValue = "False",
-        named = true,
-        positional = false,
-        doc = "Whether the action should use the built in shell environment or not."
-      ),
-      @Param(
-        name = "env",
-        type = SkylarkDict.class,
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        positional = false,
-        doc = "Sets the dictionary of environment variables."
-      ),
-      @Param(
-        name = "execution_requirements",
-        type = SkylarkDict.class,
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        positional = false,
-        doc =
-            "Information for scheduling the action. See "
-                + "<a href=\"$BE_ROOT/common-definitions.html#common.tags\">tags</a> "
-                + "for useful keys."
-      ),
-      @Param(
-        // TODO(bazel-team): The name here isn't accurate anymore. This is technically experimental,
-        // so folks shouldn't be too attached, but consider renaming to be more accurate/opaque.
-        name = "input_manifests",
-        type = SkylarkList.class,
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        positional = false,
-        doc =
-            "(Experimental) sets the input runfiles metadata; "
-                + "they are typically generated by resolve_command."
-      )
-    },
-    allowReturnNones = true,
-    useLocation = true,
-    useEnvironment = true
-  )
+  @Override
   public Runtime.NoneType action(
       SkylarkList outputs,
       Object inputs,
@@ -1252,33 +857,7 @@
     return Runtime.NONE;
   }
 
-  @SkylarkCallable(
-    name = "expand_location",
-    doc =
-        "Expands all <code>$(location ...)</code> templates in the given string by replacing "
-            + "<code>$(location //x)</code> with the path of the output file of target //x. "
-            + "Expansion only works for labels that point to direct dependencies of this rule or "
-            + "that are explicitly listed in the optional argument <code>targets</code>. "
-            + "<br/><br/>"
-            + "<code>$(location ...)</code> will cause an error if the referenced target has "
-            + "multiple outputs. In this case, please use <code>$(locations ...)</code> since it "
-            + "produces a space-separated list of output paths. It can be safely used for a "
-            + "single output file, too.",
-    parameters = {
-      @Param(name = "input", type = String.class, doc = "String to be expanded."),
-      @Param(
-        name = "targets",
-        type = SkylarkList.class,
-        generic1 = AbstractConfiguredTarget.class,
-        defaultValue = "[]",
-        named = true,
-        doc = "List of targets for additional lookup information."
-      ),
-    },
-    allowReturnNones = true,
-    useLocation = true,
-    useEnvironment = true
-  )
+  @Override
   public String expandLocation(String input, SkylarkList targets, Location loc, Environment env)
       throws EvalException {
     checkMutable("expand_location");
@@ -1292,33 +871,9 @@
     }
   }
 
-  @SkylarkCallable(
-    name = "file_action",
-    doc =
-        "DEPRECATED. Use <a href =\"actions.html#write\">ctx.actions.write</a> instead. <br>"
-            + "Creates a file write action.",
-    parameters = {
-      @Param(name = "output", type = Artifact.class, named = true, doc = "The output file."),
-      @Param(
-        name = "content",
-        type = String.class,
-        named = true,
-        doc = "The contents of the file."
-      ),
-      @Param(
-        name = "executable",
-        type = Boolean.class,
-        defaultValue = "False",
-        named = true,
-        doc = "Whether the output file should be executable (default is False)."
-      )
-    },
-    allowReturnNones = true,
-    useLocation = true,
-    useEnvironment = true
-  )
+  @Override
   public Runtime.NoneType fileAction(
-      Artifact output, String content, Boolean executable, Location loc, Environment env)
+      FileApi output, String content, Boolean executable, Location loc, Environment env)
       throws EvalException {
     checkDeprecated("ctx.actions.write", "ctx.file_action", loc, env.getSemantics());
     checkMutable("file_action");
@@ -1326,38 +881,7 @@
     return Runtime.NONE;
   }
 
-  @SkylarkCallable(
-    name = "empty_action",
-    doc =
-        "DEPRECATED. Use <a href=\"actions.html#do_nothing\">ctx.actions.do_nothing</a> instead."
-            + " <br>"
-            + "Creates an empty action that neither executes a command nor produces any "
-            + "output, but that is useful for inserting 'extra actions'.",
-    parameters = {
-      @Param(
-        name = "mnemonic",
-        type = String.class,
-        named = true,
-        positional = false,
-        doc = "A one-word description of the action, e.g. CppCompile or GoLink."
-      ),
-      @Param(
-        name = "inputs",
-        allowedTypes = {
-          @ParamType(type = SkylarkList.class),
-          @ParamType(type = SkylarkNestedSet.class),
-        },
-        generic1 = Artifact.class,
-        named = true,
-        positional = false,
-        defaultValue = "[]",
-        doc = "List of the input files of the action."
-      ),
-    },
-    allowReturnNones = true,
-    useLocation = true,
-    useEnvironment = true
-  )
+  @Override
   public Runtime.NoneType emptyAction(String mnemonic, Object inputs, Location loc, Environment env)
       throws EvalException {
     checkDeprecated("ctx.actions.do_nothing", "ctx.empty_action", loc, env.getSemantics());
@@ -1366,50 +890,10 @@
     return Runtime.NONE;
   }
 
-  @SkylarkCallable(
-    name = "template_action",
-    doc =
-        "DEPRECATED. "
-            + "Use <a href=\"actions.html#expand_template\">ctx.actions.expand_template()</a> "
-            + "instead. <br>Creates a template expansion action.",
-    parameters = {
-      @Param(
-        name = "template",
-        type = Artifact.class,
-        named = true,
-        positional = false,
-        doc = "The template file, which is a UTF-8 encoded text file."
-      ),
-      @Param(
-        name = "output",
-        type = Artifact.class,
-        named = true,
-        positional = false,
-        doc = "The output file, which is a UTF-8 encoded text file."
-      ),
-      @Param(
-        name = "substitutions",
-        type = SkylarkDict.class,
-        named = true,
-        positional = false,
-        doc = "Substitutions to make when expanding the template."
-      ),
-      @Param(
-        name = "executable",
-        type = Boolean.class,
-        defaultValue = "False",
-        named = true,
-        positional = false,
-        doc = "Whether the output file should be executable (default is False)."
-      )
-    },
-    allowReturnNones = true,
-    useLocation = true,
-    useEnvironment = true
-  )
+  @Override
   public Runtime.NoneType templateAction(
-      Artifact template,
-      Artifact output,
+      FileApi template,
+      FileApi output,
       SkylarkDict<?, ?> substitutionsUnchecked,
       Boolean executable,
       Location loc,
@@ -1421,67 +905,7 @@
     return Runtime.NONE;
   }
 
-  @SkylarkCallable(
-    name = "runfiles",
-    doc = "Creates a runfiles object.",
-    parameters = {
-      @Param(
-        name = "files",
-        type = SkylarkList.class,
-        generic1 = Artifact.class,
-        named = true,
-        defaultValue = "[]",
-        doc = "The list of files to be added to the runfiles."
-      ),
-      // TODO(bazel-team): If we have a memory efficient support for lazy list containing
-      // NestedSets we can remove this and just use files = [file] + list(set)
-      // Also, allow empty set for init
-      @Param(
-        name = "transitive_files",
-        type = SkylarkNestedSet.class,
-        generic1 = Artifact.class,
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        doc =
-            "The (transitive) set of files to be added to the runfiles. The depset should "
-                + "use the `default` order (which, as the name implies, is the default)."
-      ),
-      @Param(
-        name = "collect_data",
-        type = Boolean.class,
-        defaultValue = "False",
-        named = true,
-        doc =
-            "Whether to collect the data "
-                + "runfiles from the dependencies in srcs, data and deps attributes."
-      ),
-      @Param(
-        name = "collect_default",
-        type = Boolean.class,
-        defaultValue = "False",
-        named = true,
-        doc =
-            "Whether to collect the default "
-                + "runfiles from the dependencies in srcs, data and deps attributes."
-      ),
-      @Param(
-        name = "symlinks",
-        type = SkylarkDict.class,
-        defaultValue = "{}",
-        named = true,
-        doc = "The map of symlinks to be added to the runfiles, prefixed by workspace name."
-      ),
-      @Param(
-        name = "root_symlinks",
-        type = SkylarkDict.class,
-        defaultValue = "{}",
-        named = true,
-        doc = "The map of symlinks to be added to the runfiles."
-      )
-    },
-    useLocation = true
-  )
+  @Override
   public Runfiles runfiles(
       SkylarkList files,
       Object transitiveFiles,
@@ -1530,87 +954,7 @@
     return runfiles;
   }
 
-  @SkylarkCallable(
-    name = "resolve_command",
-    // TODO(bazel-team): The naming here isn't entirely accurate (input_manifests is no longer
-    // manifests), but this is experimental/should be opaque to the end user.
-    doc =
-        "<i>(Experimental)</i> "
-            + "Returns a tuple <code>(inputs, command, input_manifests)</code> of the list of "
-            + "resolved inputs, the argv list for the resolved command, and the runfiles metadata"
-            + "required to run the command, all of them suitable for passing as the same-named "
-            + "arguments of the <code>ctx.action</code> method.",
-    parameters = {
-      @Param(
-        name = "command",
-        type = String.class, // string
-        defaultValue = "''",
-        named = true,
-        positional = false,
-        doc = "Command to resolve."
-      ),
-      @Param(
-        name = "attribute",
-        type = String.class, // string
-        defaultValue = "None",
-        noneable = true,
-        named = true,
-        positional = false,
-        doc = "Name of the associated attribute for which to issue an error, or None."
-      ),
-      @Param(
-        name = "expand_locations",
-        type = Boolean.class,
-        defaultValue = "False",
-        named = true,
-        positional = false,
-        doc =
-            "Shall we expand $(location) variables? "
-                + "See <a href=\"#expand_location\">ctx.expand_location()</a> for more details."
-      ),
-      @Param(
-        name = "make_variables",
-        type = SkylarkDict.class, // dict(string, string)
-        noneable = true,
-        defaultValue = "None",
-        named = true,
-        positional = false,
-        doc = "Make variables to expand, or None."
-      ),
-      @Param(
-        name = "tools",
-        defaultValue = "[]",
-        type = SkylarkList.class,
-        generic1 = TransitiveInfoCollection.class,
-        named = true,
-        positional = false,
-        doc = "List of tools (list of targets)."
-      ),
-      @Param(
-        name = "label_dict",
-        type = SkylarkDict.class,
-        defaultValue = "{}",
-        named = true,
-        positional = false,
-        doc =
-            "Dictionary of resolved labels and the corresponding list of Files "
-                + "(a dict of Label : list of Files)."
-      ),
-      @Param(
-        name = "execution_requirements",
-        type = SkylarkDict.class,
-        defaultValue = "{}",
-        named = true,
-        positional = false,
-        doc =
-            "Information for scheduling the action to resolve this command. See "
-                + "<a href=\"$BE_ROOT/common-definitions.html#common.tags\">tags</a> "
-                + "for useful keys."
-      ),
-    },
-    useLocation = true,
-    useEnvironment = true
-  )
+  @Override
   public Tuple<Object> resolveCommand(
       String command,
       Object attributeUnchecked,
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/BuildConfigurationApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/BuildConfigurationApi.java
new file mode 100644
index 0000000..ad73c80
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/BuildConfigurationApi.java
@@ -0,0 +1,69 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.skylarkbuildapi;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+
+/** Interface for a configuration object which holds information about the build environment. */
+@SkylarkModule(
+    name = "configuration",
+    category = SkylarkModuleCategory.BUILTIN,
+    doc = "This object holds information about the environment in which the build is running. See "
+        + "the <a href='../rules.$DOC_EXT#configurations'>Rules page</a> for more on the general "
+        + "concept of configurations."
+)
+public interface BuildConfigurationApi {
+
+  @SkylarkCallable(name = "bin_dir", structField = true, documented = false)
+  @Deprecated
+  public FileRootApi getBinDirectory();
+
+  @SkylarkCallable(name = "genfiles_dir", structField = true, documented = false)
+  @Deprecated
+  public FileRootApi getGenfilesDirectory();
+
+  @SkylarkCallable(name = "host_path_separator", structField = true,
+      doc = "Returns the separator for PATH environment variable, which is ':' on Unix.")
+  public String getHostPathSeparator();
+
+  @SkylarkCallable(
+    name = "default_shell_env",
+    structField = true,
+    doc =
+        "A dictionary representing the static local shell environment. It maps variables "
+            + "to their values (strings)."
+  )
+  @Deprecated // Use getActionEnvironment instead.
+  public ImmutableMap<String, String> getLocalShellEnvironment();
+
+  @SkylarkCallable(
+    name = "test_env",
+    structField = true,
+    doc =
+        "A dictionary containing user-specified test environment variables and their values, "
+            + "as set by the --test_env options. DO NOT USE! This is not the complete environment!"
+  )
+  public ImmutableMap<String, String> getTestEnv();
+
+  @SkylarkCallable(name = "coverage_enabled", structField = true,
+      doc = "A boolean that tells whether code coverage is enabled for this run. Note that this "
+          + "does not compute whether a specific rule should be instrumented for code coverage "
+          + "data collection. For that, see the <a href=\"ctx.html#coverage_instrumented\"><code>"
+          + "ctx.coverage_instrumented</code></a> function.")
+  public boolean isCodeCoverageEnabled();
+}
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/FragmentCollectionApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/FragmentCollectionApi.java
new file mode 100644
index 0000000..5ddc5da
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/FragmentCollectionApi.java
@@ -0,0 +1,34 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.skylarkbuildapi;
+
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.syntax.ClassObject;
+
+/** Represents a collection of configuration fragments in Skylark. */
+@SkylarkModule(
+    name = "fragments",
+    category = SkylarkModuleCategory.NONE,
+    doc =
+        "Possible fields are "
+            + "<a href=\"android.html\">android</a>, <a href=\"apple.html\">apple</a>, "
+            + "<a href=\"cpp.html\">cpp</a>, <a href=\"java.html\">java</a>, "
+            + "<a href=\"jvm.html\">jvm</a>, and <a href=\"objc.html\">objc</a>. "
+            + "Access a specific fragment by its field name "
+            + "ex:</p><code>ctx.fragments.apple</code></p>"
+            + "Note that rules have to declare their required fragments in order to access them "
+            + "(see <a href=\"../rules.md#fragments\">here</a>).")
+public interface FragmentCollectionApi extends ClassObject {}
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkAttributesCollectionApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkAttributesCollectionApi.java
new file mode 100644
index 0000000..7092b70
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkAttributesCollectionApi.java
@@ -0,0 +1,54 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.skylarkbuildapi;
+
+import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
+import com.google.devtools.build.lib.syntax.EvalException;
+
+/**
+ * Interface for a type containing information about the attributes of a rule.
+ */
+@SkylarkModule(
+  name = "rule_attributes",
+  category = SkylarkModuleCategory.NONE,
+  doc = "Information about attributes of a rule an aspect is applied to."
+)
+public interface SkylarkAttributesCollectionApi extends SkylarkValue {
+
+  @SkylarkCallable(name = "attr", structField = true, doc = SkylarkRuleContextApi.ATTR_DOC)
+  public StructApi getAttr() throws EvalException;
+
+  @SkylarkCallable(
+      name = "executable",
+      structField = true,
+      doc = SkylarkRuleContextApi.EXECUTABLE_DOC)
+  public StructApi getExecutable() throws EvalException;
+
+  @SkylarkCallable(name = "file", structField = true, doc = SkylarkRuleContextApi.FILE_DOC)
+  public StructApi getFile() throws EvalException;
+
+  @SkylarkCallable(name = "files", structField = true, doc = SkylarkRuleContextApi.FILES_DOC)
+  public StructApi getFiles() throws EvalException;
+
+  @SkylarkCallable(
+    name = "kind",
+    structField = true,
+    doc = "The kind of a rule, such as 'cc_library'"
+  )
+  public String getRuleClassName() throws EvalException;
+}
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleContextApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleContextApi.java
new file mode 100644
index 0000000..64b50eb
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleContextApi.java
@@ -0,0 +1,896 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.skylarkbuildapi;
+
+import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.events.Location;
+import com.google.devtools.build.lib.skylarkinterface.Param;
+import com.google.devtools.build.lib.skylarkinterface.ParamType;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
+import com.google.devtools.build.lib.syntax.ClassObject;
+import com.google.devtools.build.lib.syntax.Environment;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.FuncallExpression.FuncallException;
+import com.google.devtools.build.lib.syntax.Runtime;
+import com.google.devtools.build.lib.syntax.SkylarkDict;
+import com.google.devtools.build.lib.syntax.SkylarkIndexable;
+import com.google.devtools.build.lib.syntax.SkylarkList;
+import com.google.devtools.build.lib.syntax.SkylarkList.Tuple;
+import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
+import java.util.Map;
+import javax.annotation.Nullable;
+
+/** Interface for a context object given to rule implementation functions. */
+@SkylarkModule(
+    name = "ctx",
+    category = SkylarkModuleCategory.BUILTIN,
+    doc = "The context of the rule containing helper functions and "
+        + "information about attributes, depending targets and outputs. "
+        + "You get a ctx object as an argument to the <code>implementation</code> function when "
+        + "you create a rule.")
+public interface SkylarkRuleContextApi extends SkylarkValue {
+
+  public static final String DOC_NEW_FILE_TAIL = "Does not actually create a file on the file "
+      + "system, just declares that some action will do so. You must create an action that "
+      + "generates the file. If the file should be visible to other rules, declare a rule output "
+      + "instead when possible. Doing so enables Blaze to associate a label with the file that "
+      + "rules can refer to (allowing finer dependency control) instead of referencing the whole "
+      + "rule.";
+  public static final String EXECUTABLE_DOC =
+      "A <code>struct</code> containing executable files defined in label type "
+          + "attributes marked as <code>executable=True</code>. The struct fields correspond "
+          + "to the attribute names. Each value in the struct is either a <code>file</code> or "
+          + "<code>None</code>. If an optional attribute is not specified in the rule "
+          + "then the corresponding struct value is <code>None</code>. If a label type is not "
+          + "marked as <code>executable=True</code>, no corresponding struct field is generated. "
+          + "<a href=\"https://github.com/bazelbuild/examples/blob/master/rules/actions_run/"
+          + "execute.bzl\">See example of use</a>.";
+  public static final String FILES_DOC =
+      "A <code>struct</code> containing files defined in label or label list "
+          + "type attributes. The struct fields correspond to the attribute names. The struct "
+          + "values are <code>list</code> of <code>file</code>s.  "
+          + "It is a shortcut for:"
+          + "<pre class=language-python>[f for t in ctx.attr.&lt;ATTR&gt; for f in t.files]</pre> "
+          + "In other words, use <code>files</code> to access the "
+          + "<a href=\"../rules.$DOC_EXT#requesting-output-files\">default outputs</a> of a "
+          + "dependency. "
+          + "<a href=\"https://github.com/bazelbuild/examples/blob/master/rules/depsets/foo.bzl\">"
+          + "See example of use</a>.";
+  public static final String FILE_DOC =
+      "A <code>struct</code> containing files defined in label type "
+          + "attributes marked as <code>allow_single_file</code>. The struct fields correspond "
+          + "to the attribute names. The struct value is always a <code>file</code> or "
+          + "<code>None</code>. If an optional attribute is not specified in the rule "
+          + "then the corresponding struct value is <code>None</code>. If a label type is not "
+          + "marked as <code>allow_single_file</code>, no corresponding struct field is generated. "
+          + "It is a shortcut for:"
+          + "<pre class=language-python>list(ctx.attr.&lt;ATTR&gt;.files)[0]</pre>"
+          + "In other words, use <code>file</code> to access the (singular) "
+          + "<a href=\"../rules.$DOC_EXT#requesting-output-files\">default output</a> of a "
+          + "dependency. "
+          + "<a href=\"https://github.com/bazelbuild/examples/blob/master/rules/expand_template/"
+          + "hello.bzl\">See example of use</a>.";
+  public static final String ATTR_DOC =
+      "A struct to access the values of the attributes. The values are provided by "
+          + "the user (if not, a default value is used). The attributes of the struct and the "
+          + "types of their values correspond to the keys and values of the <code>attrs</code> "
+          + "dict provided to the <code>rule</code> function. "
+          + "<a href=\"https://github.com/bazelbuild/examples/blob/master/rules/attributes/"
+          + "printer.bzl\">See example of use</a>.";
+  public static final String SPLIT_ATTR_DOC =
+      "A struct to access the values of attributes with split configurations. If the attribute is "
+          + "a label list, the value of split_attr is a dict of the keys of the split (as strings) "
+          + "to lists of the ConfiguredTargets in that branch of the split. If the attribute is a "
+          + "label, then the value of split_attr is a dict of the keys of the split (as strings) "
+          + "to single ConfiguredTargets. Attributes with split configurations still appear in the "
+          + "attr struct, but their values will be single lists with all the branches of the split "
+          + "merged together.";
+  public static final String OUTPUTS_DOC =
+      "A pseudo-struct containing all the predeclared output files, represented by "
+          + "<a href='File.html'><code>File</code></a> objects. See the "
+          + "<a href='../rules.$DOC_EXT#files'>Rules page</a> for more information and examples."
+          + "<p>This field does not exist on aspect contexts, since aspects do not have "
+          + "predeclared outputs."
+          + "<p>The fields of this object are defined as follows. It is an error if two outputs "
+          + "produce the same field name or have the same label."
+          + "<ul>"
+          + "<li>If the rule declares an <a href='globals.html#rule.outputs'><code>outputs</code>"
+          + "</a> dict, then for every entry in the dict, there is a field whose name is the key "
+          + "and whose value is the corresponding <code>File</code>."
+          + "<li>For every attribute of type <a href='attr.html#output'><code>attr.output</code>"
+          + "</a> that the rule declares, there is a field whose name is the attribute's name. "
+          + "If the target specified a label for that attribute, then the field value is the "
+          + "corresponding <code>File</code>; otherwise the field value is <code>None</code>."
+          + "<li>For every attribute of type <a href='attr.html#output_list'><code>attr.output_list"
+          + "</code></a> that the rule declares, there is a field whose name is the attribute's "
+          + "name. The field value is a list of <code>File</code> objects corresponding to the "
+          + "labels given for that attribute in the target, or an empty list if the attribute was "
+          + "not specified in the target."
+          + "<li><b>(Deprecated)</b> If the rule is marked <a href='globals.html#rule.executable'>"
+          + "<code>executable</code></a> or <a href='globals.html#rule.test'><code>test</code></a>,"
+          + "there is a field named <code>\"executable\"</code>, which is the default executable. "
+          + "It is recommended that instead of using this, you pass another file (either "
+          + "predeclared or not) to the <code>executable</code> arg of "
+          + "<a href='globals.html#DefaultInfo'><code>DefaultInfo</code></a>."
+          + "</ul>";
+
+  @SkylarkCallable(
+    name = "default_provider",
+    structField = true,
+    doc = "Deprecated. Use <a href=\"globals.html#DefaultInfo\">DefaultInfo</a> instead."
+  )
+  public ProviderApi getDefaultProvider();
+
+  @SkylarkCallable(
+    name = "actions",
+    structField = true,
+    doc = "Functions to declare files and create actions."
+  )
+  public SkylarkActionFactoryApi actions();
+
+  @SkylarkCallable(
+      name = "created_actions",
+      doc = "For rules with <a href=\"globals.html#rule._skylark_testable\">_skylark_testable"
+          + "</a> set to <code>True</code>, this returns an "
+          + "<a href=\"globals.html#Actions\">Actions</a> provider representing all actions "
+          + "created so far for the current rule. For all other rules, returns <code>None</code>. "
+          + "Note that the provider is not updated when subsequent actions are created, so you "
+          + "will have to call this function again if you wish to inspect them. "
+          + "<br/><br/>"
+          + "This is intended to help write tests for rule-implementation helper functions, which "
+          + "may take in a <code>ctx</code> object and create actions on it.")
+  public SkylarkValue createdActions() throws EvalException;
+
+  @SkylarkCallable(name = "attr", structField = true, doc = ATTR_DOC)
+  public StructApi getAttr() throws EvalException;
+
+  @SkylarkCallable(name = "split_attr", structField = true, doc = SPLIT_ATTR_DOC)
+  public StructApi getSplitAttr() throws EvalException;
+
+  @SkylarkCallable(name = "executable", structField = true, doc = EXECUTABLE_DOC)
+  public StructApi getExecutable() throws EvalException;
+
+  @SkylarkCallable(name = "file", structField = true, doc = FILE_DOC)
+  public StructApi getFile() throws EvalException;
+
+  @SkylarkCallable(name = "files", structField = true, doc = FILES_DOC)
+  public StructApi getFiles() throws EvalException;
+
+  @SkylarkCallable(
+    name = "workspace_name",
+    structField = true,
+    doc = "Returns the workspace name as defined in the WORKSPACE file."
+  )
+  public String getWorkspaceName() throws EvalException;
+
+  @SkylarkCallable(name = "label", structField = true, doc = "The label of this rule.")
+  public Label getLabel() throws EvalException;
+
+  @SkylarkCallable(
+    name = "fragments",
+    structField = true,
+    doc = "Allows access to configuration fragments in target configuration."
+  )
+  public FragmentCollectionApi getFragments() throws EvalException;
+
+  @SkylarkCallable(
+    name = "host_fragments",
+    structField = true,
+    doc = "Allows access to configuration fragments in host configuration."
+  )
+  public FragmentCollectionApi getHostFragments() throws EvalException;
+
+  @SkylarkCallable(
+    name = "configuration",
+    structField = true,
+    doc =
+        "Returns the default configuration. See the <a href=\"configuration.html\">"
+            + "configuration</a> type for more details."
+  )
+  public BuildConfigurationApi getConfiguration() throws EvalException;
+
+  @SkylarkCallable(
+    name = "host_configuration",
+    structField = true,
+    doc =
+        "Returns the host configuration. See the <a href=\"configuration.html\">"
+            + "configuration</a> type for more details."
+  )
+  public BuildConfigurationApi getHostConfiguration() throws EvalException;
+
+  @SkylarkCallable(
+    name = "coverage_instrumented",
+    doc = "Returns whether code coverage instrumentation should be generated when performing "
+        + "compilation actions for this rule or, if <code>target</code> is provided, the rule "
+        + "specified by that Target. (If a non-rule or a Skylark rule Target is provided, this "
+        + "returns False.) Checks if the sources of the current rule (if no Target is provided) or"
+        + "the sources of Target should be instrumented based on the --instrumentation_filter and"
+        + "--instrument_test_targets config settings. "
+        + "This differs from <code>coverage_enabled</code> in the <a href=\"configuration.html\">"
+        + "configuration</a>, which notes whether coverage data collection is enabled for the "
+        + "entire run, but not whether a specific target should be instrumented.",
+    parameters = {
+      @Param(
+          name = "target",
+          type = TransitiveInfoCollectionApi.class,
+          defaultValue = "None",
+          noneable = true,
+          named = true,
+          doc = "A Target specifying a rule. If not provided, defaults to the current rule.")
+    }
+  )
+  public boolean instrumentCoverage(Object targetUnchecked) throws EvalException;
+
+  @SkylarkCallable(
+    name = "features",
+    structField = true,
+    doc = "Returns the set of features that are enabled for this rule."
+  )
+  public ImmutableList<String> getFeatures() throws EvalException;
+
+  @SkylarkCallable(
+    name = "bin_dir",
+    structField = true,
+    doc = "The root corresponding to bin directory."
+  )
+  public FileRootApi getBinDirectory() throws EvalException;
+
+  @SkylarkCallable(
+    name = "genfiles_dir",
+    structField = true,
+    doc = "The root corresponding to genfiles directory."
+  )
+  public FileRootApi getGenfilesDirectory() throws EvalException;
+
+  @SkylarkCallable(structField = true, doc = OUTPUTS_DOC)
+  public ClassObject outputs() throws EvalException;
+
+  @SkylarkCallable(
+    structField = true,
+    doc =
+        "Returns rule attributes descriptor for the rule that aspect is applied to."
+            + " Only available in aspect implementation functions."
+  )
+  public SkylarkAttributesCollectionApi rule() throws EvalException;
+
+  @SkylarkCallable(
+    structField = true,
+    name = "aspect_ids",
+    doc =
+        "Returns a list ids for all aspects applied to the target."
+            + " Only available in aspect implementation functions."
+  )
+  public ImmutableList<String> aspectIds() throws EvalException;
+
+  @SkylarkCallable(
+    structField = true,
+    doc = "Dictionary (String to String) of configuration variables."
+  )
+  public SkylarkDict<String, String> var() throws EvalException;
+
+  @SkylarkCallable(structField = true, doc = "Toolchains required for this rule.")
+  public SkylarkIndexable toolchains() throws EvalException;
+
+  @SkylarkCallable(doc = "Splits a shell command to a list of tokens.", documented = false)
+  public SkylarkList<String> tokenize(String optionString) throws FuncallException, EvalException;
+
+  @SkylarkCallable(
+    doc =
+        "Expands all references to labels embedded within a string for all files using a mapping "
+            + "from definition labels (i.e. the label in the output type attribute) to files. "
+            + "Deprecated.",
+    documented = false
+  )
+  public String expand(
+      @Nullable String expression, SkylarkList<Object> artifacts, Label labelResolver)
+      throws EvalException, FuncallException;
+
+  @SkylarkCallable(
+    name = "new_file",
+    doc =
+        "DEPRECATED. Use <a href=\"actions.html#declare_file\">ctx.actions.declare_file</a>. <br>"
+            + "Creates a file object with the given filename, in the current package. "
+            + DOC_NEW_FILE_TAIL,
+    parameters = {
+      @Param(
+        name = "filename",
+        type = String.class,
+        doc = "The path of the new file, relative to the current package."
+      )
+    }
+  )
+  public FileApi newFile(String filename) throws EvalException;
+
+  @SkylarkCallable(documented = false)
+  public FileApi newFile(FileRootApi root, String filename) throws EvalException;
+
+  @SkylarkCallable(
+    name = "new_file",
+    doc =
+        "Creates a new file object in the same directory as the original file. "
+            + DOC_NEW_FILE_TAIL,
+    parameters = {
+      @Param(
+        name = "sibling_file",
+        type = FileApi.class,
+        doc = "A file that lives in the same directory as the newly created file."
+      ),
+      @Param(
+        name = "basename",
+        type = String.class,
+        doc = "The base name of the newly created file."
+      )
+    }
+  )
+  public FileApi newFile(FileApi baseArtifact, String newBaseName) throws EvalException;
+
+  @SkylarkCallable(documented = false)
+  public FileApi newFile(FileRootApi root, FileApi baseArtifact, String suffix)
+      throws EvalException;
+
+  @SkylarkCallable(
+    name = "experimental_new_directory",
+    documented = false,
+    parameters = {
+      @Param(name = "name", type = String.class),
+      @Param(
+        name = "sibling",
+        type = FileApi.class,
+        defaultValue = "None",
+        noneable = true,
+        named = true
+      )
+    }
+  )
+  public FileApi newDirectory(String name, Object siblingArtifactUnchecked) throws EvalException;
+
+  @SkylarkCallable(documented = false)
+  public boolean checkPlaceholders(String template, SkylarkList<Object> allowedPlaceholders)
+      throws EvalException;
+
+  @SkylarkCallable(
+    doc = "<b>Deprecated.</b> Use <code>ctx.var</code> to access the variables instead.<br>"
+        + "Returns a string after expanding all references to \"Make variables\". The variables "
+        + "must have the following format: <code>$(VAR_NAME)</code>. Also, <code>$$VAR_NAME"
+        + "</code> expands to <code>$VAR_NAME</code>. Parameters:"
+        + "<ul><li>The name of the attribute (<code>string</code>). It's only used for error "
+        + "reporting.</li>\n"
+        + "<li>The expression to expand (<code>string</code>). It can contain references to "
+        + "\"Make variables\".</li>\n"
+        + "<li>A mapping of additional substitutions (<code>dict</code> of <code>string</code> : "
+        + "<code>string</code>).</li></ul>\n"
+        + "Examples:"
+        + "<pre class=language-python>\n"
+        + "ctx.expand_make_variables(\"cmd\", \"$(MY_VAR)\", {\"MY_VAR\": \"Hi\"})  # == \"Hi\"\n"
+        + "ctx.expand_make_variables(\"cmd\", \"$$PWD\", {})  # == \"$PWD\"\n"
+        + "</pre>"
+        + "Additional variables may come from other places, such as configurations. Note that "
+        + "this function is experimental.")
+  public String expandMakeVariables(
+      String attributeName, String command, final Map<String, String> additionalSubstitutions)
+      throws EvalException;
+
+  @SkylarkCallable(
+    name = "info_file",
+    structField = true,
+    documented = false,
+    doc =
+        "Returns the file that is used to hold the non-volatile workspace status for the "
+            + "current build request."
+  )
+  public FileApi getStableWorkspaceStatus() throws InterruptedException, EvalException;
+
+  @SkylarkCallable(
+    name = "version_file",
+    structField = true,
+    documented = false,
+    doc =
+        "Returns the file that is used to hold the volatile workspace status for the "
+            + "current build request."
+  )
+  public FileApi getVolatileWorkspaceStatus() throws InterruptedException, EvalException;
+
+  @SkylarkCallable(
+    name = "build_file_path",
+    structField = true,
+    documented = true,
+    doc = "Returns path to the BUILD file for this rule, relative to the source root."
+  )
+  public String getBuildFileRelativePath() throws EvalException;
+
+  @SkylarkCallable(
+    name = "action",
+    doc =
+        "DEPRECATED. Use <a href=\"actions.html#run\">ctx.actions.run()</a> or"
+            + " <a href=\"actions.html#run_shell\">ctx.actions.run_shell()</a>. <br>"
+            + "Creates an action that runs an executable or a shell command."
+            + " You must specify either <code>command</code> or <code>executable</code>.\n"
+            + "Actions and genrules are very similar, but have different use cases. Actions are "
+            + "used inside rules, and genrules are used inside macros. Genrules also have make "
+            + "variable expansion.",
+    parameters = {
+      @Param(
+        name = "outputs",
+        type = SkylarkList.class,
+        generic1 = FileApi.class,
+        named = true,
+        positional = false,
+        doc = "List of the output files of the action."
+      ),
+      @Param(
+        name = "inputs",
+        allowedTypes = {
+          @ParamType(type = SkylarkList.class),
+          @ParamType(type = SkylarkNestedSet.class),
+        },
+        generic1 = FileApi.class,
+        defaultValue = "[]",
+        named = true,
+        positional = false,
+        doc = "List of the input files of the action."
+      ),
+      @Param(
+        name = "executable",
+        type = Object.class,
+        allowedTypes = {
+          @ParamType(type = FileApi.class),
+          @ParamType(type = String.class),
+          @ParamType(type = Runtime.NoneType.class),
+        },
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        positional = false,
+        doc = "The executable file to be called by the action."
+      ),
+      @Param(
+        name = "tools",
+        allowedTypes = {
+          @ParamType(type = SkylarkList.class),
+          @ParamType(type = SkylarkNestedSet.class),
+        },
+        generic1 = FileApi.class,
+        defaultValue = "unbound",
+        named = true,
+        positional = false,
+        doc =
+            "List of the any tools needed by the action. Tools are inputs with additional "
+                + "runfiles that are automatically made available to the action."
+      ),
+      @Param(
+        name = "arguments",
+        allowedTypes = {
+          @ParamType(type = SkylarkList.class),
+        },
+        defaultValue = "[]",
+        named = true,
+        positional = false,
+        doc =
+            "Command line arguments of the action."
+                + "Must be a list of strings or actions.args() objects."
+      ),
+      @Param(
+        name = "mnemonic",
+        type = String.class,
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        positional = false,
+        doc = "A one-word description of the action, e.g. CppCompile or GoLink."
+      ),
+      @Param(
+        name = "command",
+        type = Object.class,
+        allowedTypes = {
+          @ParamType(type = String.class),
+          @ParamType(type = SkylarkList.class, generic1 = String.class),
+          @ParamType(type = Runtime.NoneType.class),
+        },
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        positional = false,
+        doc =
+            "Shell command to execute. It is usually preferable to "
+                + "use <code>executable</code> instead. "
+                + "Arguments are available with <code>$1</code>, <code>$2</code>, etc."
+      ),
+      @Param(
+        name = "progress_message",
+        type = String.class,
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        positional = false,
+        doc =
+            "Progress message to show to the user during the build, "
+                + "e.g. \"Compiling foo.cc to create foo.o\"."
+      ),
+      @Param(
+        name = "use_default_shell_env",
+        type = Boolean.class,
+        defaultValue = "False",
+        named = true,
+        positional = false,
+        doc = "Whether the action should use the built in shell environment or not."
+      ),
+      @Param(
+        name = "env",
+        type = SkylarkDict.class,
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        positional = false,
+        doc = "Sets the dictionary of environment variables."
+      ),
+      @Param(
+        name = "execution_requirements",
+        type = SkylarkDict.class,
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        positional = false,
+        doc =
+            "Information for scheduling the action. See "
+                + "<a href=\"$BE_ROOT/common-definitions.html#common.tags\">tags</a> "
+                + "for useful keys."
+      ),
+      @Param(
+        // TODO(bazel-team): The name here isn't accurate anymore. This is technically experimental,
+        // so folks shouldn't be too attached, but consider renaming to be more accurate/opaque.
+        name = "input_manifests",
+        type = SkylarkList.class,
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        positional = false,
+        doc =
+            "(Experimental) sets the input runfiles metadata; "
+                + "they are typically generated by resolve_command."
+      )
+    },
+    allowReturnNones = true,
+    useLocation = true,
+    useEnvironment = true
+  )
+  public Runtime.NoneType action(
+      SkylarkList outputs,
+      Object inputs,
+      Object executableUnchecked,
+      Object toolsUnchecked,
+      Object arguments,
+      Object mnemonicUnchecked,
+      Object commandUnchecked,
+      Object progressMessage,
+      Boolean useDefaultShellEnv,
+      Object envUnchecked,
+      Object executionRequirementsUnchecked,
+      Object inputManifestsUnchecked,
+      Location loc,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+    name = "expand_location",
+    doc =
+        "Expands all <code>$(location ...)</code> templates in the given string by replacing "
+            + "<code>$(location //x)</code> with the path of the output file of target //x. "
+            + "Expansion only works for labels that point to direct dependencies of this rule or "
+            + "that are explicitly listed in the optional argument <code>targets</code>. "
+            + "<br/><br/>"
+            + "<code>$(location ...)</code> will cause an error if the referenced target has "
+            + "multiple outputs. In this case, please use <code>$(locations ...)</code> since it "
+            + "produces a space-separated list of output paths. It can be safely used for a "
+            + "single output file, too.",
+    parameters = {
+      @Param(name = "input", type = String.class, doc = "String to be expanded."),
+      @Param(
+        name = "targets",
+        type = SkylarkList.class,
+        generic1 = TransitiveInfoCollectionApi.class,
+        defaultValue = "[]",
+        named = true,
+        doc = "List of targets for additional lookup information."
+      ),
+    },
+    allowReturnNones = true,
+    useLocation = true,
+    useEnvironment = true
+  )
+  public String expandLocation(String input, SkylarkList targets, Location loc, Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+    name = "file_action",
+    doc =
+        "DEPRECATED. Use <a href =\"actions.html#write\">ctx.actions.write</a> instead. <br>"
+            + "Creates a file write action.",
+    parameters = {
+      @Param(name = "output", type = FileApi.class, named = true, doc = "The output file."),
+      @Param(
+        name = "content",
+        type = String.class,
+        named = true,
+        doc = "The contents of the file."
+      ),
+      @Param(
+        name = "executable",
+        type = Boolean.class,
+        defaultValue = "False",
+        named = true,
+        doc = "Whether the output file should be executable (default is False)."
+      )
+    },
+    allowReturnNones = true,
+    useLocation = true,
+    useEnvironment = true
+  )
+  public Runtime.NoneType fileAction(
+      FileApi output, String content, Boolean executable, Location loc, Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+    name = "empty_action",
+    doc =
+        "DEPRECATED. Use <a href=\"actions.html#do_nothing\">ctx.actions.do_nothing</a> instead."
+            + " <br>"
+            + "Creates an empty action that neither executes a command nor produces any "
+            + "output, but that is useful for inserting 'extra actions'.",
+    parameters = {
+      @Param(
+        name = "mnemonic",
+        type = String.class,
+        named = true,
+        positional = false,
+        doc = "A one-word description of the action, e.g. CppCompile or GoLink."
+      ),
+      @Param(
+        name = "inputs",
+        allowedTypes = {
+          @ParamType(type = SkylarkList.class),
+          @ParamType(type = SkylarkNestedSet.class),
+        },
+        generic1 = FileApi.class,
+        named = true,
+        positional = false,
+        defaultValue = "[]",
+        doc = "List of the input files of the action."
+      ),
+    },
+    allowReturnNones = true,
+    useLocation = true,
+    useEnvironment = true
+  )
+  public Runtime.NoneType emptyAction(String mnemonic, Object inputs, Location loc, Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+    name = "template_action",
+    doc =
+        "DEPRECATED. "
+            + "Use <a href=\"actions.html#expand_template\">ctx.actions.expand_template()</a> "
+            + "instead. <br>Creates a template expansion action.",
+    parameters = {
+      @Param(
+        name = "template",
+        type = FileApi.class,
+        named = true,
+        positional = false,
+        doc = "The template file, which is a UTF-8 encoded text file."
+      ),
+      @Param(
+        name = "output",
+        type = FileApi.class,
+        named = true,
+        positional = false,
+        doc = "The output file, which is a UTF-8 encoded text file."
+      ),
+      @Param(
+        name = "substitutions",
+        type = SkylarkDict.class,
+        named = true,
+        positional = false,
+        doc = "Substitutions to make when expanding the template."
+      ),
+      @Param(
+        name = "executable",
+        type = Boolean.class,
+        defaultValue = "False",
+        named = true,
+        positional = false,
+        doc = "Whether the output file should be executable (default is False)."
+      )
+    },
+    allowReturnNones = true,
+    useLocation = true,
+    useEnvironment = true
+  )
+  public Runtime.NoneType templateAction(
+      FileApi template,
+      FileApi output,
+      SkylarkDict<?, ?> substitutionsUnchecked,
+      Boolean executable,
+      Location loc,
+      Environment env)
+      throws EvalException;
+
+  @SkylarkCallable(
+    name = "runfiles",
+    doc = "Creates a runfiles object.",
+    parameters = {
+      @Param(
+        name = "files",
+        type = SkylarkList.class,
+        generic1 = FileApi.class,
+        named = true,
+        defaultValue = "[]",
+        doc = "The list of files to be added to the runfiles."
+      ),
+      // TODO(bazel-team): If we have a memory efficient support for lazy list containing
+      // NestedSets we can remove this and just use files = [file] + list(set)
+      // Also, allow empty set for init
+      @Param(
+        name = "transitive_files",
+        type = SkylarkNestedSet.class,
+        generic1 = FileApi.class,
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        doc =
+            "The (transitive) set of files to be added to the runfiles. The depset should "
+                + "use the `default` order (which, as the name implies, is the default)."
+      ),
+      @Param(
+        name = "collect_data",
+        type = Boolean.class,
+        defaultValue = "False",
+        named = true,
+        doc =
+            "Whether to collect the data "
+                + "runfiles from the dependencies in srcs, data and deps attributes."
+      ),
+      @Param(
+        name = "collect_default",
+        type = Boolean.class,
+        defaultValue = "False",
+        named = true,
+        doc =
+            "Whether to collect the default "
+                + "runfiles from the dependencies in srcs, data and deps attributes."
+      ),
+      @Param(
+        name = "symlinks",
+        type = SkylarkDict.class,
+        defaultValue = "{}",
+        named = true,
+        doc = "The map of symlinks to be added to the runfiles, prefixed by workspace name."
+      ),
+      @Param(
+        name = "root_symlinks",
+        type = SkylarkDict.class,
+        defaultValue = "{}",
+        named = true,
+        doc = "The map of symlinks to be added to the runfiles."
+      )
+    },
+    useLocation = true
+  )
+  public RunfilesApi runfiles(
+      SkylarkList files,
+      Object transitiveFiles,
+      Boolean collectData,
+      Boolean collectDefault,
+      SkylarkDict<?, ?> symlinks,
+      SkylarkDict<?, ?> rootSymlinks,
+      Location loc)
+      throws EvalException;
+
+  @SkylarkCallable(
+    name = "resolve_command",
+    // TODO(bazel-team): The naming here isn't entirely accurate (input_manifests is no longer
+    // manifests), but this is experimental/should be opaque to the end user.
+    doc =
+        "<i>(Experimental)</i> "
+            + "Returns a tuple <code>(inputs, command, input_manifests)</code> of the list of "
+            + "resolved inputs, the argv list for the resolved command, and the runfiles metadata"
+            + "required to run the command, all of them suitable for passing as the same-named "
+            + "arguments of the <code>ctx.action</code> method.",
+    parameters = {
+      @Param(
+        name = "command",
+        type = String.class, // string
+        defaultValue = "''",
+        named = true,
+        positional = false,
+        doc = "Command to resolve."
+      ),
+      @Param(
+        name = "attribute",
+        type = String.class, // string
+        defaultValue = "None",
+        noneable = true,
+        named = true,
+        positional = false,
+        doc = "Name of the associated attribute for which to issue an error, or None."
+      ),
+      @Param(
+        name = "expand_locations",
+        type = Boolean.class,
+        defaultValue = "False",
+        named = true,
+        positional = false,
+        doc =
+            "Shall we expand $(location) variables? "
+                + "See <a href=\"#expand_location\">ctx.expand_location()</a> for more details."
+      ),
+      @Param(
+        name = "make_variables",
+        type = SkylarkDict.class, // dict(string, string)
+        noneable = true,
+        defaultValue = "None",
+        named = true,
+        positional = false,
+        doc = "Make variables to expand, or None."
+      ),
+      @Param(
+        name = "tools",
+        defaultValue = "[]",
+        type = SkylarkList.class,
+        generic1 = TransitiveInfoCollectionApi.class,
+        named = true,
+        positional = false,
+        doc = "List of tools (list of targets)."
+      ),
+      @Param(
+        name = "label_dict",
+        type = SkylarkDict.class,
+        defaultValue = "{}",
+        named = true,
+        positional = false,
+        doc =
+            "Dictionary of resolved labels and the corresponding list of Files "
+                + "(a dict of Label : list of Files)."
+      ),
+      @Param(
+        name = "execution_requirements",
+        type = SkylarkDict.class,
+        defaultValue = "{}",
+        named = true,
+        positional = false,
+        doc =
+            "Information for scheduling the action to resolve this command. See "
+                + "<a href=\"$BE_ROOT/common-definitions.html#common.tags\">tags</a> "
+                + "for useful keys."
+      ),
+    },
+    useLocation = true,
+    useEnvironment = true
+  )
+  public Tuple<Object> resolveCommand(
+      String command,
+      Object attributeUnchecked,
+      Boolean expandLocations,
+      Object makeVariablesUnchecked,
+      SkylarkList tools,
+      SkylarkDict<?, ?> labelDictUnchecked,
+      SkylarkDict<?, ?> executionRequirementsUnchecked,
+      Location loc,
+      Environment env)
+      throws EvalException;
+}
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/TransitiveInfoCollectionApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/TransitiveInfoCollectionApi.java
new file mode 100644
index 0000000..3b3d1ce
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/TransitiveInfoCollectionApi.java
@@ -0,0 +1,58 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.skylarkbuildapi;
+
+import com.google.devtools.build.lib.skylarkinterface.Param;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
+
+/**
+ * Interface for a build target.
+ */
+@SkylarkModule(
+  name = "Target",
+  category = SkylarkModuleCategory.BUILTIN,
+  doc =
+      "A BUILD target. It is essentially a <code>struct</code> with the following fields:"
+          + "<ul>"
+          + "<li><h3 id=\"modules.Target.label\">label</h3><code><a class=\"anchor\" "
+          + "href=\"Label.html\">Label</a> Target.label</code><br>The identifier of the "
+          + "target.</li>"
+          + "<li><h3 id=\"modules.Target.files\">files</h3><code><a class=\"anchor\" "
+          + "href=\"depset.html\">depset</a> Target.files </code><br>The set of "
+          + "<a class=\"anchor\" href=\"File.html\">File</a>s produced directly by this "
+          + "target.</li>"
+          + "<li><h3 id=\"modules.Target.aspect_ids\">aspect_ids</h3><code><a class=\"anchor\""
+          + "href=\"list.html\">list</a> Target.aspect_ids </code><br>The list of "
+          + "<a class=\"anchor\" href=\"ctx.html#aspect_id\">aspect_id</a>s applied to this "
+          + "target.</li>"
+          + "<li><h3 id=\"modules.Target.extraproviders\">Extra providers</h3>For rule targets all "
+          + "additional providers provided by this target are accessible as <code>struct</code> "
+          + "fields. These extra providers are defined in the <code>struct</code> returned by the "
+          + "rule implementation function.</li>"
+          + "</ul>"
+)
+public interface TransitiveInfoCollectionApi {
+
+  @SkylarkCallable(
+    name = "output_group",
+    documented = false, //  TODO(dslomov): document.
+    parameters = {
+      @Param(name = "group_name", type = String.class, doc = "Output group name", named = true)
+    })
+  SkylarkNestedSet outputGroup(String group);
+}