> Three things still have to be built, server by server

> citation

Nope, as long as the MCP server exposes enough metadata to be cited (mostly trivial), citation is a job of the client/LLM.

> trust

Also just a function of the client. The server can't aid here at all as it's inherently untrustworthy in the system.

> measurement

Maybe. Though it's debatable how much measurement _each_ server needs, and whether that actually gives meaningful insight to optimize. This might as well be measured outside of the servers, in the client/a centralized logging system that also sees surrounding context.