@chancerydaily From what I understand, you generally don't want to be too flowery. Like, if it's text, just transcribe it directly, no foreword. If it's an image, explain the key points of what one is seeing. The idea is to give someone without sight enough context to understand what's being posted without wasting their time with endless descriptors (text-to-speech isn't always the fastest talker).
Mentioning color would be fine, if it's key to what's being posted, but leave it out if it's not relevant.
Alt-text has been around for a long time, so there are many guides if you want more info. This one is a very reputable source for building the web: https://www.w3.org/WAI/tutorials/images/