Tags should describe the question, not its answers ...
After all, that's why questions get tags and answers don't. Tags are meant to enable people to find lists of questions on a particular topic - either because they're looking for something which they can answer, or because they have a question about that topic themselves and want to know if it's already been asked. If people want to find answers, they can do so using the
is:a search function, and include tags in that search if desired.
Questions shouldn't be retagged according to the kind of answers they've received. The question should be able to stand alone as a valid question about a given subject even without looking at the answers. Related discussion: Should we retag story ID questions with the story name?
... but the question may specify a particular kind of desired answer.
It's perfectly acceptable for an OP to specify in their question that they're looking for answers of a particular type and won't accept any other kind of answer. "
Please only give answers based on X" is a perfectly valid part of a question. I can't think of any examples of "types of answer" which are already associated with particular tags on this site, but if such a case comes up, then it might well be reasonable to tag the question according to the type of answer it's seeking.
(An example of this on the sister site SFF is the star-wars-legends tag, which can be used on a question to indicate that Legends sources are acceptable in answers; without this tag, it is assumed that only canon sources are acceptable. When the OP isn't experienced enough with the site to know about this tagging practice, other users will often ask in the comments "are Legends sources acceptable?" and then edit in the tag if the OP says yes.)
Of course, such requirements are 100% the OP's prerogative. Nobody else should have the right to say "this question should accept answers of type X as well as type Y", and edits which change the OP's intent, including if they do so by changing the tags, should be rolled back.