WordPress at a glance
action is not described

wp_add_nav_menu_item action-hook . WP 4.4.0

Fires immediately after a new navigation menu item has been added.

Usage

add_action( 'wp_add_nav_menu_item', 'action_function_name_7144', 10, 3 );
function action_function_name_7144( $menu_id, $menu_item_db_id, $args ){
	// action...
}
$menu_id(int)
ID of the updated menu.
$menu_item_db_id(int)
ID of the new menu item.
$args(array)
An array of arguments used to update/add the menu item.

Where the hook is called

wp_update_nav_menu_item()
wp-includes/nav-menu.php 509
do_action( 'wp_add_nav_menu_item', $menu_id, $menu_item_db_id, $args );

Where the hook is used (in WP core)

Does not used.