We have a tag solvability, with excerpt:
A question about how a puzzle can be solved.
However, "solvability" seems to imply that you'd be asking about whether a puzzle can be solved. New users especially won't figure this out, and I end up editing this tag into quite a few puzzles where it was missing.
Is this a problem? Should we rename it? (My first idea is how-to-solve, but feel free to suggest others)