The alt text displayed seems to be the raw LaTeX syntax, and there is no mechanism I can find to change the alt text.
I think this point went unanswered. Why is raw LaTeX syntax added to the rendered math image alt-text and not something more usable like Mathspeak or Clearspeak? (asking from the perspective of a default/native MathJax user and commenting on the EPUB/PDF behavior of MathJax math expressions)
This seems to be a capability of MathJax—as exhibited in their MathJax Speech Converter—so why can’t this be the default behavior? Raw LaTeX is not an accessible form of alt-text. Is the related GitHub Issue—Improve accessibility of [math] images generated for EPUB and Digital PDF exports #128—in scope for 2026 development?
Also, when rendering MathML to images both the MathML and the LaTeX annotation fallback are added as alt-text, creating a sort of double-speak. For example, mathml contentLaTeX fallback would result in an image rendered with the alt-text “mathml content LaTeX content“.