Host vs Client Semantics

[ghost]

Pre-submission Checklist

• I have checked that this question would not be more appropriate as an issue in a specific repository
• I have searched existing discussions and documentation for answers

Question Category

• Protocol Specification
• SDK Usage
• Server Implementation
• General Implementation
• Documentation
• Other

Your Question

In the MCP Client Quickstart, the MCPClient class manages the user message history. Is this overloading of the term "Client"?

My understanding is that this is a host responsibility. New to MCP, so I might be misunderstanding.

This quickstart confused me when trying to understand the distinction between "client" and "host". It's also a bit unclear to me why someone would create a standalone client outside of a host. Thanks in advance for the help!

[evalstate]

You're right to clarify this!

For the specification, the [MCP] Client is the component that manages the 1:1 relationship with the [MCP] Server, while the Host application manages the interaction with the LLM and Clients.

In most other places the terms are used interchangeably for convenience! :)

[ghost]

Thanks @evalstate for the confirmation.

As a newcomer to MCP, it wasn't immediately obvious what the distinction between clients and the host was. I ended up more confused when I looked at the MCP Client Quickstart and saw the MCPClient class managing message context. Just wanted to share that beginner's perspective in case it's helpful in improving the docs.

Regardless, thanks for your reply!

[evalstate]

Oh, I know. it's one of my little "things" too! I think this is something we could make it a little easier - perhaps an info box around the quickstart....