This shortcode does not produce a content itself. When you use it inside post content you enclose a part of content inside this shortcode, e.g.
[user_role_editor ...]content to show[/user_role_editor]
You can use this logic inside your template code:

if (current_user_can('agent')) {
  echo 'You can see this';
} else {
  echo 'You can not see this';

Or set this restriction for the ‘agent’ role using ‘Posts View’ button from posts view restriction module. You may use some category ID assigned to all post of that type for that.