You'd want unique descriptions on each directory. Google wouldn't necessarily penalize you if 50 directories had the same description of your site, but those listings/links would be less valuable in Google's eyes and it's likely only one of them would be indexed.

The more work you put in the more value you'd get. My advice concentrate on the top 10 to 20 directory sites and give each a thoughtful, unique description.

Happy to provide further insights if you want to have a call.