> to an LLM that can call tools (since MCP essentially turns an API into a LLM tool).

"Tools" is literally an API call

> With MCP, the agent sees a bunch of tools it can call,

Yes, the agent first calls a specific API that returns the schema for that particular server. It's literally the same.

> One more very important factor is authorization, which no one seems to mention in these discussions.

Yes, API calls to services are often gated behind auth. OAuth that MCP uses is from 2006, and its version 2 is from 2012. What do you think it was created for?

> the MCP provider has auditability: is this a call from a human or from a LLM? That's important in Enterprise

We had "differentiate these two accounts and audit log their activity" probably since the 1950s

> there's also more benefits like being able to "elicit" user input

Two-way communication is also a thing since the 1950s, probably.