Sampling with Tools

mcp-sampling-with-tools.md

sequenceDiagram
    participant Server
    participant Client as Client/Host
    actor User
    participant LLM

    Note over Server,Client: Initial request with tools
    Server->>Client: sampling/createMessage<br/>(messages + tools)

    Note over Client,User: Human-in-the-loop review
    Client->>User: Present request for approval
    User-->>Client: Approve/modify

    Note over Client: Convert MCP messages and tool descriptions<br/>to LLM messages and tool descriptions

    Client->>LLM: Send request with tools to LLM
    LLM-->>Client: Response with tool_use<br/>(stopReason: "toolUse")

    Client->>User: Present tool calls for review
    User-->>Client: Approve tool calls
    
    Note over Client: Convert LLM tool calls to MCP tool_use content blocks
    
    Client-->>Server: Return tool_use response

    Note over Server: Execute tool(s)
    Server->>Server: Run get_weather("Paris")<br/>Run get_weather("London")

    Note over Server,Client: Issue new sampling request with tool results
    Server->>Client: sampling/createMessage<br/>(history + tool_results + tools)

    Client->>User: Present continuation
    User-->>Client: Approve

    Note over Client: Convert MCP messages and tool results<br/>to LLM messages and tool results

    Client->>LLM: Forward with tool results
    LLM-->>Client: Final text response<br/>(stopReason: "endTurn")

    Client->>User: Present response
    User-->>Client: Approve
    
    Note over Client: Convert LLM response to MCP content blocks
    
    Client-->>Server: Return final response

    Note over Server: Server processes result<br/>(may continue conversation...)

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