diff --git a/core/modules/migrate/src/Plugin/migrate/process/MenuLinkParent.php b/core/modules/migrate/src/Plugin/migrate/process/MenuLinkParent.php
index 0cb7c68..487f6ec 100644
--- a/core/modules/migrate/src/Plugin/migrate/process/MenuLinkParent.php
+++ b/core/modules/migrate/src/Plugin/migrate/process/MenuLinkParent.php
@@ -15,7 +15,28 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
- * This plugin figures out menu link parent plugin IDs.
+ * Determines the menu link parent plugin IDs.
+ *
+ * The menu_link_parent process plugin figures out menu link parent plugin IDs.
+ *
+ * The source is an array of three values:
+ *   - parent_id: The parent link ID (plid) is the mlid of the link above in the hierarchy, or zero if the link is at the top level in 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 path this link points to.
+ *
+ * Example:
+ *
+ * @code
+ * process:
+ *   parent:
+ *     plugin: menu_link_parent
+ *     source:
+ *       - plid
+ *       - menu_name
+ *       - parent_link_path
+ * @endcode
+ *
+ * @see \Drupal\migrate\Plugin\MigrateProcessInterface
  *
  * @MigrateProcessPlugin(
  *   id = "menu_link_parent"
@@ -64,9 +85,24 @@ public static function create(ContainerInterface $container, array $configuratio
   }
 
   /**
-   * {@inheritdoc}
    *
    * Find the parent link GUID.
+   * Performs the associated process.
+   *
+   * @param string $value
+   *   The input string.
+   * @param \Drupal\migrate\MigrateExecutableInterface $migrate_executable
+   *   The migration in which this process is being executed.
+   * @param \Drupal\migrate\Row $row
+   *   The row from the source to process.
+   * @param string $destination_property
+   *   The destination property currently worked on. This is only used together
+   *   with the $row above.
+   *
+   * @return string
+   *   The sub string of $value.
+   *
+   * @throws \Drupal\migrate\MigrateSkipRowException
    */
   public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
     $parent_id = array_shift($value);