Screen reader accessibility: How “talky” should my button be?

I'm trying to improve screen reader support on our webapp, but I'm struggling a bit with what the best practice is for our buttons. Our current pattern looks something like this

If I focus on the button, should the screen reader say...

...Choose file, required?

...Upload personal letter: choose file?

...Upload personal letter: choose file. Allowed filetypes: doc, docx. Required?

We're currently going for the more talky version, but our team has limited experience with screen reader users and how they're used, so a push in the right direction would be very helpful. Thank you. :)