sampling_server

MCP Sampling Example Server

This example demonstrates how to implement an MCP server that uses sampling to request LLM completions from clients.

Features

• Sampling Support: The server can request LLM completions from clients that support sampling
• Tool Integration: Shows how to use sampling within tool implementations
• Bidirectional Communication: Demonstrates server-to-client requests

Tools

ask_llm

Asks the LLM a question using sampling. This tool demonstrates how servers can leverage client-side LLM capabilities.

Parameters:

• question (required): The question to ask the LLM
• system_prompt (optional): System prompt to provide context

greet

A simple greeting tool that doesn't use sampling, for comparison.

Parameters:

• name (required): Name of the person to greet

Usage

Build and run the server:

go build -o sampling_server
./sampling_server

The server communicates via stdio and expects to be connected to an MCP client that supports sampling.

Implementation Details

1. Enable Sampling: The server calls mcpServer.EnableSampling() to declare sampling capability
2. Request Sampling: Tools use mcpServer.RequestSampling(ctx, request) to send sampling requests to the client
3. Handle Responses: The server receives and processes the LLM responses from the client via bidirectional stdio communication
4. Response Routing: Incoming responses are automatically routed to the correct pending request using request IDs

Testing

Use the companion sampling_client example to test this server:

cd ../sampling_client
go build -o sampling_client
./sampling_client ../sampling_server/sampling_server