diff --git a/src/main/java/com/googlesource/gerrit/plugins/zuul/util/DependsOnExtractor.java b/src/main/java/com/googlesource/gerrit/plugins/zuul/util/DependsOnExtractor.java
index 456eacf..5860940 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/zuul/util/DependsOnExtractor.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/zuul/util/DependsOnExtractor.java
@@ -21,6 +21,7 @@
 /** Extracts dependency information from texts. */
 public class DependsOnExtractor {
   public List<String> extract(String commitMessage) {
+    // TODO Add support for URL based `Depends-On` references.
     List<String> dependsOn = new ArrayList<>();
     Pattern pattern =
         Pattern.compile(
diff --git a/src/main/java/com/googlesource/gerrit/plugins/zuul/util/NeededByFetcher.java b/src/main/java/com/googlesource/gerrit/plugins/zuul/util/NeededByFetcher.java
index e11fd22..7475fb4 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/zuul/util/NeededByFetcher.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/zuul/util/NeededByFetcher.java
@@ -45,6 +45,7 @@
 
   public List<ChangeInfo> fetchForChangeKey(Change.Key key)
       throws BadRequestException, AuthException, PermissionBackendException {
+    // TODO Add support for URL based `Depends-On` references.
     String keyString = key.toString();
     List<ChangeInfo> neededBy = new ArrayList<>();
 
diff --git a/src/main/resources/Documentation/about.md b/src/main/resources/Documentation/about.md
index 4abe78f..dfa5148 100644
--- a/src/main/resources/Documentation/about.md
+++ b/src/main/resources/Documentation/about.md
@@ -14,5 +14,8 @@
 
 The cross repository dependencies are also exposed through the [REST API](rest-api-changes.html).
 
+This plugin currently does not support URL based dependencies, but only
+`Change-Id` dependencies, which got deprecated in Zuul v3.
+
 [cross repository dependencies]: https://zuul-ci.org/docs/zuul/discussion/gating.html#cross-project-dependencies
 [Dependency cycles]: https://zuul-ci.org/docs/zuul/discussion/gating.html#cycles