As far as I can tell MCP is just "we bothered to document our api in a programatically readable way".
Just generate CLI tools, with docs, from MCP servers on demand.
Theres transport and context management. A cross agent status cache with semaphore over a testing harness driving a browser that can rewind and retry is much easier for agents to drive from mcp than selenium or whatever is fashionable these days. Didn't replace unit testing per se but to rca and fix it's a much better tool.
It's exactly that, but I don't see the issue. API+Docs under a single URL looks like a win for me. It also warrants a new name.
In enterprise integrations, that is just not an option. MCP has pretty much taken over there.