The proper way to do this for a blind student would surely be some kind of physical manipulatives, not verbal descriptions. The thing is, I don’t have any blind students currently, and if I did, we’d work on individual accommodation and assistance.
With this alt text, I’m just trying to get •something• in there to be at least minimally accessible: head start on those accommodation, something helpful if I ever share this online, etc. If there’s any way for text to convey the spatial relationships, that would be better than the text I have.