diff --git a/core/modules/migrate/src/Plugin/MigratePluginManagerInterface.php b/core/modules/migrate/src/Plugin/MigratePluginManagerInterface.php
index a5fa116..d6ed39f 100644
--- a/core/modules/migrate/src/Plugin/MigratePluginManagerInterface.php
+++ b/core/modules/migrate/src/Plugin/MigratePluginManagerInterface.php
@@ -7,12 +7,22 @@
 interface MigratePluginManagerInterface extends PluginManagerInterface {
 
   /**
-   * {@inheritdoc}
+   * Creates a pre-configured instance of a migration plugin.
    *
+   * A specific createInstance method is necessary to pass the migration on.
+   *
+   * @param string $plugin_id
+   *   The ID of the plugin being instantiated.
+   * @param array $configuration
+   *   An array of configuration relevant to the plugin instance.
    * @param \Drupal\migrate\Plugin\MigrationInterface $migration
    *   The migration context in which the plugin will run.
    *
-   * A specific createInstance method is necessary to pass the migration on.
+   * @return object
+   *   A fully configured plugin instance.
+   *
+   * @throws \Drupal\Component\Plugin\Exception\PluginException
+   *   If the instance cannot be created, such as if the ID is invalid.
    */
   public function createInstance($plugin_id, array $configuration = [], MigrationInterface $migration = NULL);
 
diff --git a/core/modules/migrate_drupal/src/Plugin/MigrateCckFieldPluginManagerInterface.php b/core/modules/migrate_drupal/src/Plugin/MigrateCckFieldPluginManagerInterface.php
index 2460d17..19e93d1 100644
--- a/core/modules/migrate_drupal/src/Plugin/MigrateCckFieldPluginManagerInterface.php
+++ b/core/modules/migrate_drupal/src/Plugin/MigrateCckFieldPluginManagerInterface.php
@@ -8,13 +8,23 @@
 interface MigrateCckFieldPluginManagerInterface extends MigratePluginManagerInterface {
 
   /**
-   * {@inheritdoc}
+   * Creates a pre-configured instance of a migration plugin.
+   *
+   * This createInstance method uses a field type instead of a plugin ID to
+   * create an instance of the plugin.
    *
    * @param string $field_type
    *   The cck field type which is being migrated.
+   * @param array $configuration
+   *   An array of configuration relevant to the plugin instance.
+   * @param \Drupal\migrate\Plugin\MigrationInterface $migration
+   *   The migration context in which the plugin will run.
    *
-   * This createInstance method uses a field type instead of a plugin ID to
-   * create an instance of the plugin.
+   * @return object
+   *   A fully configured plugin instance.
+   *
+   * @throws \Drupal\Component\Plugin\Exception\PluginException
+   *   If the instance cannot be created, such as if the ID is invalid.
    */
   public function createInstance($field_type, array $configuration = [], MigrationInterface $migration = NULL);