I find it depends a lot on the model used and what the MCP does. I have agents trawl research papers, and just giving the raw API to DeepSeek leads to lots of wasted tokens and bad use of the API options. Here, wrapping the API to minimize the available options and providing sane defaults fixes that. Perhaps a frontier model can use the API directly without issues, but for DeepSeek a good MCP wrapper is very useful. Besides that, having control and limits in the MCP is very useful for some ratelimited APIs