I've been maintaining a Twitter bot providing a number of tools around image descriptions AKA alt text for a bit. It has overlapping sets of commands for both tagging and DMs, the list of which are in the pinned tweet.
The bot is primarily used for OCR of posted images to provide a retweetable version with alt text, but other commands such as AI image description and searches of the alt-text.org library are becoming more common.
The code is available on GitHub, and is MIT licensed: https://github.com/alt-text-org/AltTextCrew