Documentation and APIs can be both machine and human readable at the same time. For my impression, MCP is compating symptoms. In a well constructed system, there would be no need to write dedicated documentation or APIs for LLMs.

By the way, I am new to GraphQL and was amazed how it reduced the boilerplate I had to write for REST in my (classical ORM) project. In a single-person team, this allows me to rapidly write frontends. With libraries such as https://gqty.dev/ I basically write no more glue code. These are probably not the needs you have as an enterprise.