Drupal 7 Simple Ajax Module returning 404
The first arg to user_access is mandatory, so you need to provide it in hook_menu via access arguments. The default for access callback is already user_access as it happens, so you can omit that:

$items['ajax-bookmark'] = array(
  'page callback' =&gt; 'bookmark_ajax_add_article',
  'access arguments' =&gt; array('access content'), // Or whatever permission makes sense.
  'type' =&gt; MENU_CALLBACK,
);


After you clear caches the page should be accessible.

Incidentally, you don't need to use jQuery.ready when you're inside a Drupal behavior attach method, as those are only ever invoked on DOM ready anyway.