Update attachment metadata fails

If you want to update title and description you should not use wp_update_attachment_metadata attachment title and description is not a meta it’s a main post detail (attachment is custom post), you can do this with following code.

$attachment = array(
  'ID' => $id,
  'post_title' => $title,
  'post_content' => $description
);
// now update main post body
wp_update_post( $attachment );