Something I've wondered with alt text because I'm not used to it, is it better to be brief and give a general idea or in depth on what you put in to it to give a clearer picture for those who need it? I don't know which is preferred but want to be accessible.

you are allowed two thousand words as your canvas, -per image-, your blessing and your curse. I like starting it brief, and sometimes adding extra information about the image. sometimes i hide stuff there as well.

I also wonder this as I want to help

Brief and to the point and, most importantly--capturing the right context. Don't waste time with fluff and irrelevant details bc someone still has to sit there and listen to it. *WHY* did you post the image? What information does it convey? That's the context missing that you need to provide.

Some people are poets, some people are bullet points; as long as the image is generally conveyed in words, i think it's all fantastic

Since the tech to help the visually impaired usually use a TTS to actually read the text, i assume a brief & clear description at the first part of the ALT text is important but you can go full poets afterwards since skipping is probably possible if the person isn't interested in what was described