diff --git a/core/java/android/accessibilityservice/AccessibilityService.java b/core/java/android/accessibilityservice/AccessibilityService.java
index 834c878900987..cae95e308f415 100644
--- a/core/java/android/accessibilityservice/AccessibilityService.java
+++ b/core/java/android/accessibilityservice/AccessibilityService.java
@@ -1846,6 +1846,13 @@ public abstract class AccessibilityService extends Service {
 
     /**
      * Returns a list of system actions available in the system right now.
+     * <p>
+     * System actions that correspond to the global action constants will have matching action IDs.
+     * For example, an with id {@link #GLOBAL_ACTION_BACK} will perform the back action.
+     * </p>
+     * <p>
+     * These actions should be called by {@link #performGlobalAction}.
+     * </p>
      *
      * @return A list of available system actions.
      */
diff --git a/core/java/android/view/accessibility/AccessibilityManager.java b/core/java/android/view/accessibility/AccessibilityManager.java
index dc87453bd867a..6a109253a27c8 100644
--- a/core/java/android/view/accessibility/AccessibilityManager.java
+++ b/core/java/android/view/accessibility/AccessibilityManager.java
@@ -1275,7 +1275,14 @@ public final class AccessibilityManager {
 
     /**
      * Register the provided {@link RemoteAction} with the given actionId
-     *
+     * <p>
+     * To perform established system actions, an accessibility service uses the GLOBAL_ACTION
+     * constants in {@link android.accessibilityservice.AccessibilityService}. To provide a
+     * customized implementation for one of these actions, the id of the registered system action
+     * must match that of the corresponding GLOBAL_ACTION constant. For example, to register a
+     * Back action, {@code actionId} must be
+     * {@link android.accessibilityservice.AccessibilityService#GLOBAL_ACTION_BACK}
+     * </p>
      * @param action The remote action to be registered with the given actionId as system action.
      * @param actionId The id uniquely identify the system action.
      * @hide