This. If you are running your agent loop, MCP does nothing.

MCP is an inter-process (or inter-system) communication standard, and it's extremely successful at that. But some people try to shoehorn it into a single system where it makes for a cumbersome fit, like having your service talk to itself via MCP as a subprocess just for the sake of "hey, we have MCP".

If you own your loop AND your business logic lives in the same codebase/process as your agent loop, you don't need MCP at all, period. Just use a good agent framework like PydanticAI, define your tools (and have your framework forward your docstrings/arguments into the context) and you're golden!