Alt tags on tweet images

I learned this morning via a comment that Twitter supports alt text descriptions for images. I didn't think that it did, and said that it didn't, but someone kindly corrected me.

When I post equations as images on this site, I always include the LaTeX source code in an alt tag. That way someone using a screen reader can determine the content of the equation. It also helps me if I need to go back and change an equation. I'd like to do the same on Twitter.

Unfortunately, it seems support for this feature is inconsistent. Maybe it's new. The software I use to manage my Twitter accounts apparently doesn't offer a way to add alt text.

When I use Twitter via its web site, I am able to write alt text but not able to read it. Maybe you have to have accessibility features turned on, which would be unfortunate. People who do not use screen readers occasionally benefit from being able to read photo descriptions. I could imagine, for example, that someone might be curious to see the LaTeX code I used to create an equation image.

I tried a couple experiments, one on my personal account and one on my AlgebraFact account. On the latter, I posted an image of the quadratic formula with the text description

 x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

When I look at the tweet while logged into my AlgebraFact account, I see a little black box in the lower left corner of the image with ALT" in white letters.

I do not see the same box on an image I posted from my personal account. When I log into my personal account, I no longer see the ALT box on the AlgebraFact tweet but I see one on an image I posted.

Question and request

It appears that with default settings, users cannot see image descriptions. What do you have to do to see the descriptions?

I intend to always put LaTeX source in the alt tag of equation images on this site. If you run across an equation without alt text, please let me know.

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