Skills are mostly snake oil, the way people use them (the aspiration to download kung foo from a celebrity). There was a time when maybe it mattered (last year), but with good repos and good prompts today's agents can find exactly what they need without any skills. "Skills" as developer macros can be useful, but at most those are things shared with the team (in the repo), not something you download from the internet.…
Same with mcp. I want them to use the jsdelivr cdn instead of them scraping github against the rate limit. etc. But if I dont explicitly state to strictly use the $%!$@@! mcp for searching in repositories they simply ignore the mcp and even if clearly instructed, they still often fall back to gh.
Putting every detailed instruction in the AGENTS.md would just unnecessarily bloat the context and it works well enough to just instruct them in the AGENTS.md when to use which skill. Yet I agree that Skills are not some voodoo magic to provide your model super capabilities.