Use this tag for questions asking about "problem books", "exercise books", and their solutions.
So the tag should be used for questions about problem books, solution manuals, etc. But many people do not read tag-excerpt. So the tag is used simply for any exercises (which is not surprising, if the poster chooses tag only based on the name of the tag).
Should we rename the tag? Maybe to problem-books or something similar?
Or would it be better to get rid of the tag completely? We already have the tag books (which was made synonym of reference-request) and book-recommendation (which was discussed here) for questions about books.