Isn't part of the issue that LLM's are relatively bad at REST and json and all that?
I remember like 2 years ago there was big hype/revolution around ChatGPT finally being able to return ONLY valid json when you asked it to. So apparently LLMs are not that good at scripting without mistakes.
Having said that, I honestly have no clue what MCP looks like or is lol :p
MCP is just json.
But to your last point: go look it up, have a read through their client/server implementations (for your language of choice). It doesn't actually take that long because the concept is actually rather simple, so I totally recommend it.
MCP is a form of JSON-RPC over HTTP, so I don't think it has anything to do with that.