Comment by paulddraper
5 hours ago
> No major models have any direct knowledge of MCP.
Claude and ChatGPT both support MCP, as does the OpenAI Agents SDK.
(If you mean the LLM itself, it is "known" at least as much as any other protocol. For whatever that means.)
>it is "known" at least as much as any other protocol.
No. It is not. Please understand what the LLM's are doing. Claude nor ChatGPT nor any major model knows what MCP is.
They know how to function & tool call. They have zero trained data on MCP.
That is a factual statement, not an opinion.
This is probably a semantics problem. You’re right. The models don’t know how to mcp. The harness they run in does though (Claude code, Claude desktop, etc), and dynamically exposes mcp tools as tool calls.
>dynamically exposes mcp tools as tool calls.
It doesn't even do that. It's not magic.
HN loves inventing semantics problems around AI. It's gotten really, really annoying and I'm not sure the people doing it are even close to understanding it.
That is an easily falsifiable statement. If I ask ChatGPT or Claude what MCP is Model Context Protocol comes up, and furthermore it can clearly explain what MCP does. That seems unlikely to be a coincidental hallucination.
Training data =/= web search
Both ChatGPT and Claude will perform web searches when you ask them a question, which the fact that you got this confused is ironically topical.
But you're still misunderstanding the principle point because at some point these models will undoubtedly have access to that data and be trained on it.
But they didn't need to be, because LLM function & tool calling is already trained on these models and MCP does not augment this functionality in any way.
2 replies →
> That is a factual statement,
I think most people, even most devs, don't actually know how crappy an MCP client is built, and that it's essentially an MITM approach and that the client sends the LLM on the other end a crappy pretext of what tools are mounted and how to call their methods in a JSON, and then tries to intelligently guess what response was a tool call.
And that intelligent guess is where it gets interesting for pentesting, because you cannot guess anything failsafe.
(pedantry)it's something humans are talking about a lot, so up-to-date models do know about it...
Most likely! It's hard to qualify which specific models and version I'm talking about because they're constantly being updated.
But the point is that function & tool calling was already built in. If you take a model from before "MCP" was even referenced on the web it will still _PERFECTLY_ interact with not only other MCP servers and clients but any other API as well.
> They have zero trained data on MCP.
They have significant data trained on MCP.
> They know how to function & tool call.
Right. You can either use MCP to transmit those tool calls, or you can create some other interface.
>They have significant data trained on MCP.
No they don't lol.