In a reply to your image post you can tag either @alttext.bsky.social@alt-text.bsky.social and they will generate alt text for your previous image post and place it in a reply to your tag. Please utilise their invaluable service - it makes everything more accessible.

You can also enable this option in your settings, which requires you to always add alt text before posting an imagine to help you remember.

so I just tried both and the one sans dash was quite descriptive, while the one with the dash failed completely. I only have 5 posts, so you'll quickly see what I mean if you take a look.

when I saw your previous post, I was actually wondering if there was a way to do it for existing posts! thanx!