For me (actually trying to get shit done using this stuff) it's validation.
Being able to have a verifiable input/output structure is key. I suppose you can do that with a regular http api call (json) but where do you document the openapi/schema stuff? Oh yeah...something like mcp.
I agree that mcp isn't as refined as it should be, but when used properly it's better than having it burn thru tokens by scraping around web content.
Yup, routing is key. Just like how we've had RAG so we don't have to add every biz doc to the context.
I agree with the general idea that models are better trained to use popular cli tools like directory navigation etc, but outside of ls and ps etc the difference isn't really there, new clis are just as confusing to the model as new mcps.