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Comment by lolinder | Hacker News Reader

It's a pretty bad spec that has a lot of artifacts of having been generated by an LLM. But at least it exists!

Yeah it is not a well thought spec. There is a big confusion about what is a MCP Client and what is a MCP Host. Which is a useless separation as what they call in the spec a client is just a connection to a server while MCP host is what is a real client (the apps using MCP like claude desktop, cli tools, etc).

But the host application does much more than just connect to MCP servers, as the host is one-to-many client connections. The host application also has OTHER client connections to AI agents and so-forth.

I think it can be confusing in general it’s like understanding X11 where the client-server relationship is conceptually flipped. :)

> But the host application does much more than just connect to MCP servers, as the host is one-to-many client connections. The host application also has OTHER client connections to AI agents and so-forth.

Yes, that is the case, but they could have called just connections, a MCP Client (host) keeps multiple open connections to MCP servers. Everywhere in the docs and in the internet peoplE MCP Client the app connecting to mcp servers, not MCP hosts.

I had that same intial reaction but I think it makes sense if you think of it in terms of software development. There are many different MCP clients being developed that are just that - clients. They don't take care of hosting the LLM or any other functionality of the application but are meant to be plugged into existing applications to enable MCP support. So from that perspective, the difference is useful, as it refers to code developed by different people.

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