diff --git a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkAttrModule.java b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkAttrModule.java
index 9230f66ca98a7a..db1048f9f0d9b0 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkAttrModule.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkAttrModule.java
@@ -330,7 +330,7 @@ private static ImmutableList<ImmutableSet<StarlarkProviderIdentifier>> getProvid
 
     for (Object o : starlarkList) {
       if (!(o instanceof Sequence)) {
-        throw Starlark.errorf(errorMsg, PROVIDERS_ARG, "an element of type " + Starlark.type(o));
+        throw Starlark.errorf(errorMsg, argumentName, "an element of type " + Starlark.type(o));
       }
       for (Object value : (Sequence) o) {
         if (!isProvider(value)) {
diff --git a/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/StarlarkRuleFunctionsApi.java b/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/StarlarkRuleFunctionsApi.java
index 2a82a6ee45632b..9a8467fc01a830 100644
--- a/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/StarlarkRuleFunctionsApi.java
+++ b/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/StarlarkRuleFunctionsApi.java
@@ -447,9 +447,10 @@ StarlarkCallable rule(
             defaultValue = "[]",
             doc =
                 "This attribute allows this aspect to inspect other aspects. The value must be a "
-                    + "list containing individual providers or lists of providers. For example, "
-                    + "<code>[FooInfo, BarInfo, [BazInfo, QuxInfo]]</code> is a "
-                    + "valid value."
+                    + "list containing either individual providers or lists of providers but not "
+                    + "both. For example, <code>[[FooInfo], [BarInfo], [BazInfo, QuxInfo]]</code> "
+                    + "is a valid value while <code>[FooInfo, BarInfo, [BazInfo, QuxInfo]]</code> "
+                    + "is not valid."
                     + ""
                     + "<p>An unnested list of providers will automatically be converted to a list "
                     + "containing one list of providers. That is, "
@@ -459,8 +460,8 @@ StarlarkCallable rule(
                     + "<p>To make another aspect (e.g. <code>other_aspect</code>) visible to this "
                     + "aspect, <code>other_aspect</code> must provide all providers from at least "
                     + "one of the lists. In the example of "
-                    + "<code>[FooInfo, BarInfo, [BazInfo, QuxInfo]]</code>, this aspect can only "
-                    + "see <code>other_aspect</code> if and only if <code>other_aspect</code> "
+                    + "<code>[[FooInfo], [BarInfo], [BazInfo, QuxInfo]]</code>, this aspect can "
+                    + "only see <code>other_aspect</code> if and only if <code>other_aspect</code> "
                     + "provides <code>FooInfo</code> *or* <code>BarInfo</code> *or* both "
                     + "<code>BazInfo</code> *and* <code>QuxInfo</code>."),
         @Param(name = "provides", named = true, defaultValue = "[]", doc = PROVIDES_DOC),