[cstrahan]

What whoknowsidont is trying to say (IIUC): the models aren't trained on particular MCP use. Yes, the models "know" what MCP is. But the point is that they don't necessarily have MCP details baked in -- if they did, there would be no point in having MCP support serving prompts / tool descriptions.

Well, arguably descriptions could be beneficial for interfaces that let you interactively test MCP tools, but that's certainly not the main reason. The main reason is that the models need to be informed about what the MCP server provides, and how to use it (where "how to use it" in this context means "what is the schema and intent behind the specific inputs/outputs" -- tool calls are baked into the training, and the OpenAI docs give a good example: https://platform.openai.com/docs/guides/function-calling).