[_ck_]

The function is tricky in how it works, many WP/bbPress functions now use the generic $args call instead of breaking it down by field.

First it checks if what’s passed to it is a number, if so, the number is treaded as a specific forum id request.

If it’s NOT a number, then it’s checked if it’s not empty, and then if it’s a string and there’s no problem using it in an array. If so, then it’s used as the before element.

To bypass those situations, you’d have to send it an array

Something like:

$args = array( 'id' => 1, 'before' => ' [ ', 'after' => ' ] ' );

forum_description($args);

Where you could leave out any of those elements inside args if you didn’t want it, like the id, after, etc.