diff -u b/core/modules/toolbar/js/toolbar.js b/core/modules/toolbar/js/toolbar.js
--- b/core/modules/toolbar/js/toolbar.js
+++ b/core/modules/toolbar/js/toolbar.js
@@ -241,8 +241,11 @@
    * Ajax command to set the toolbar subtrees.
    *
    * @param {Drupal.Ajax} ajax
+   *   {@link Drupal.Ajax} object created by {@link Drupal.ajax}.
    * @param {object} response
+   *   JSON response from the Ajax request.
    * @param {number} [status]
+   *   XMLHttpRequest status.
    */
   Drupal.AjaxCommands.prototype.setToolbarSubtrees = function (ajax, response, status) {
     Drupal.toolbar.setSubtrees.resolve(response.subtrees);