@BunnyAiden @MissSnarkerson It's also possible to describe the picture in a way that doesn't use up your character limit!
When you preview the pic, hover over the lower portion and it should display a bar you can type in!

@ThisQueerBashesBack @BunnyAiden @MissSnarkerson Oooooh!! I didn't know this, either!! :D Thanks; I can make use of that in the future. ^_^

@BunnyAiden @MissSnarkerson Also, as a non-blind disabled person I don't think it's necessarily ableist if you weren't yet aware of it. We can only act on the knowledge that we have! And changing our habits is hard! So, if you make a mistake with images every now and again, try to remember to be gentle with yourself. Know better, do better.

@ThisQueerBashesBack @MissSnarkerson ^^^^ couldn't have said it better

@ThisQueerBashesBack @BunnyAiden @MissSnarkerson I'm with Gay Cyborg Comrade here!! We all make mistakes. ^_^ We can learn from them.

@ThisQueerBashesBack @BunnyAiden @MissSnarkerson One thing you should know about that -- at least in my Mastodon client, if you mouse over the image after you attach it, it'll say "Describe for the visually impaired", and provide a separate text-box that will turn it into alt-text.
That means blind people will still get the description, but it won't be in the main body of your toot.
(Example attached.)

@MissSnarkerson @BunnyAiden @ThisQueerBashesBack If you hover a mouse over the image in the previous toot, it says "A dog, sat at a typewriter, looking like it is typing", but it doesn't use up any of the toot characters.

@stealthmunchkin That's good. ^^ although I noticed that doesn't seem to work on mobile.

@stealthmunchkin @ThisQueerBashesBack @BunnyAiden Doesn't appear to work in my mobile app, but works perfectly (...and easily!) in the web app!