Every skill conforms to the Agent Skills specification
The specification is the one format every host reads. A skill that violates it fails to load, and most hosts fail silently, so the author sees a skill that never triggers and no error saying why.
Observable check
a specification validator exits 0 for every directory under skills/. oss-skill ships one at scripts/validate.mjs in its own installed directory, which reads files, needs nothing installed, and runs on Node 22 or later and on Bun.