Are URLs in alt text usable?

In a recent edit I made on UX Stack Exchange, I added some alt text to an image that contained the URL of a page at which the reader could see a textual version of the content in the image.

However, I'm unsure whether including links in alt text like this is actually useful. How will a screen reader handle such a URL? Does software typically used by blind or vision-impaired users provide a means to visit such URLs - for instance, by enabling them to copy the alt text to the clipboard? Or is such a link effectively impossible to follow for the audience at which it is aimed?