Is it "self-described" in the sense I can get a list of endpoints or methods, with a human- (or LLM-) readable description for each - or does it supply actual schemata that I could also use with non-AI clients?

(Even if only the former, it would of course be a huge step forward, as I could have the LLM generate schemata. Also, at least, everyone is standardizing on a base protocol now, and a way to pass command names, arguments, results, etc. That's already a huge step forward in contrast to arbitrary Rest+JSON or even HTTP APIs)