diff --git a/core/modules/migrate/src/Plugin/migrate/process/MenuLinkParent.php b/core/modules/migrate/src/Plugin/migrate/process/MenuLinkParent.php
index 0cb7c68..ff23640 100644
--- a/core/modules/migrate/src/Plugin/migrate/process/MenuLinkParent.php
+++ b/core/modules/migrate/src/Plugin/migrate/process/MenuLinkParent.php
@@ -15,7 +15,35 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
- * This plugin figures out menu link parent plugin IDs.
+ * Determines the parent of a menu link.
+ *
+ * If the parent cannot be ascertained then a MigrateSkipRowException is thrown.
+ *
+ * The source is an array of three values:
+ * - parent_id: The numeric ID of the parent menu link, or 0 if the link is at
+ *   the top level of its menu.
+ * - menu_name: The menu name. All links with the same menu name (such as
+ *   'navigation') are part of the same menu.
+ * - parent_link_path: The Drupal path or external URL this link points to.
+ *
+ * Example:
+ *
+ * @code
+ * process:
+ *   parent:
+ *     plugin: menu_link_parent
+ *     source:
+ *       - '20'
+ *       - 'admin'
+ *       - 'admin/structure'
+ * @endcode
+ *
+ * In this example the parent_id of '20' will be looked up and returned from
+ * amongst the already migrated IDs. If it is not found then the
+ * parent_link_path of 'admin/structure' is loaded from the 'admin' menu, the
+ * given menu_name.
+ *
+ * @see \Drupal\migrate\Plugin\MigrateProcessInterface
  *
  * @MigrateProcessPlugin(
  *   id = "menu_link_parent"
@@ -65,8 +93,6 @@ public static function create(ContainerInterface $container, array $configuratio
 
   /**
    * {@inheritdoc}
-   *
-   * Find the parent link GUID.
    */
   public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
     $parent_id = array_shift($value);