While the image insertion tool in the rich text editor includes a field for alternate text, the system file picker does not. When organizations add image files, such as for badges and theme logos, they cannot meet accessibility requirements for the images.  

Acceptance requirements

As a user adding a file image in the system, I will know this is done when:

• Upon adding a file, either through drag and drop or file selection from my computer, the system displays an optional field for adding alternate text

• Upon subsequently accessing the uploaded image file, I can view and edit the alternate text field

• Visually impaired users can be informed of the image text via screen reader

Since the file picker modal does not display when adding files via drag/drop, maybe the easiest approach is to just include the field in that modal? (see screenshot) Users would have to take the extra step of opening this modal after drag/drop, but that's much less complex to support than launching the modal upon the drag/drop action.