Right now the description of Custom Reports is "Create a custom report by choosing record type, fields, and linked record types" on the create reports page. This implies that by selecting custom reports from the create menu, you'll be able to create a custom report though now you can only run it from there and need to create it in the gear menu. This language will need to be update to reflect what a user can actually do from that page before the feature is added.
What do you want the description to be?