Thank you for raising this idea! We also think it's a great one. I'm happy to say that lists descriptions are now available in beta given it also comes with the ability to create custom properties for your Lists!
We currently maintain a shared document outside Hubspot to explain how the various lists should be used. We would not need that if there was a "Description" field on the lists themselves.
Agree this would be a very useful feature. When you have lots of lists, it's difficult to see which ones are candidates for being removed if you don't know their purpose.
Thank you for raising this idea! We also think it's a great one. I'm happy to say that lists descriptions are now available in beta given it also comes with the ability to create custom properties for your Lists!