diff --git a/core/src/main/java/jenkins/management/Badge.java b/core/src/main/java/jenkins/management/Badge.java
index 67528ad56b32..6ee8fb25c493 100644
--- a/core/src/main/java/jenkins/management/Badge.java
+++ b/core/src/main/java/jenkins/management/Badge.java
@@ -48,6 +48,10 @@
  *  A badge might display the same information as an {@link AdministrativeMonitor}. While an {@link AdministrativeMonitor}
  *  can be disabled, a badge will always be shown. E.g. the badge of {@link OldDataMonitor.ManagementLinkImpl} always shows the number of old data entries.
  *
+ *  <p>
+ *  A badge can also be used in a {@code <l:task .../>} to show information on the right of the link in the sidepanel,
+ *  e.g. to show number of available plugin updates.
+ *
  *  @since 2.385
  */
 @ExportedBean
diff --git a/core/src/main/resources/lib/layout/task.jelly b/core/src/main/resources/lib/layout/task.jelly
index 70bdd9f06b60..ec17b8e92a53 100644
--- a/core/src/main/resources/lib/layout/task.jelly
+++ b/core/src/main/resources/lib/layout/task.jelly
@@ -77,9 +77,9 @@ THE SOFTWARE.
       (onclick supersedes this except in the context menu.)
       (since 1.512)
     </st:attribute>
-    <st:attribute name="badge">
+    <st:attribute name="badge" type="jenkins.management.Badge">
       If set, displays the value as a small badge on the right side of the sidepanel item.
-      @since TODO
+      (since 2.401)
     </st:attribute>
     <st:attribute name="confirmationMessage">
       Message to use for confirmation, if requested; defaults to title.