Embedding image descriptions would be nice

I want to be able to embed image descriptions in the image like you can do on websites, so it appears when you hover your mouse on the image and it is read by screen readers, but it does not appear otherwise.

A detailed image description can get pretty long, and currently the only way to add it is to put in a message everyone will see, which can bother people who have problems with long messages (for example people on mobile or people with reading disabilities who struggle when confronted with a wall of text)

In addition, this option should be very easy to use, like adding a second text box named "add an image description" on the image posting dialog box. This way it does not force people to learn HTML or something in order to add image descriptions. This would also remind people who might have forgotten that they can and should add an image description when posting an image.

Finally, the guide on how to post images should explain how to add image descriptions and mention that you should do it.