At my company Parallel AI, I just built an extremely well documented openapi spec and then MCP builds from that. Complete alignment with UI/API/MCP so there is no extra work.

Are others doing this?

It seemed obvious to me, but I don't hear others saying it.

The challenge with this is that it often causes a proliferation of MCP tools which bloats context, which is one of the reasons that MCP was created.

Yes, for .NET and Java backend stuff, it is basically extending what is already there.

On low code/no code tools, you get additional metadata for webhooks.