Isn't this what sampling is for?
My main disappointment with sampling right now is the very limited scope. It'd be nice to support some universal tool calling syntax or something. Otherwise a reasonably complicated MCP Server is still going to need a direct LLM connect.
I don't get how MCP could create a wrapper for all possible LLM inference APIs or why it'd be desirable (that's an awful long leash for me to give out on my API key)