MCP Runner

A Rust library for running and interacting with Model Context Protocol (MCP) servers locally.

Overview

MCP Runner provides a complete solution for managing Model Context Protocol servers in Rust applications. It enables:

- Starting and managing MCP server processes
- Configuring multiple servers through a unified interface
- Communicating with MCP servers using JSON-RPC
- Listing and calling tools exposed by MCP servers
- Accessing resources provided by MCP servers
- Proxying Server-Sent Events (SSE) to enable clients to connect to MCP servers

Installation

Add this to your Cargo.toml:

[dependencies]
mcp-runner = "0.3.1"

Quick Start

Here's a simple example of using MCP Runner to start a server and call a tool:

use mcp_runner::{McpRunner, error::Result};
use serde::{Deserialize, Serialize};
use serde_json::json;
#[tokio::main]

async fn main() -> Result<()> {

    // Create runner from config file

    let mut runner = McpRunner::from_config_file("config.json")?;
// Start all servers and the SSE proxy if configured

    let (server_ids, proxy_started) = runner.start_all_with_proxy().await;

    let server_ids = server_ids?;
if proxy_started {

        println!("SSE proxy started successfully");

    }
// Get client for interacting with a specific server

    let server_id = runner.get_server_id("fetch")?;

    let client = runner.get_client(server_id)?;
// Initialize the client

    client.initialize().await?;
// List available tools

    let tools = client.list_tools().await?;

    println!("Available tools:");

    for tool in tools {

        println!("  - {}: {}", tool.name, tool.description);

    }
// Call the fetch tool with structured input

    let fetch_result = client.call_tool("fetch", &json!({

        "url": "https://modelcontextprotocol.io"

    })).await?;

    println!("Fetch result: {}", fetch_result);
// Stop the server when done

    runner.stop_server(server_id).await?;
Ok(())

}

Observability

This library uses the tracing crate for logging and diagnostics. To enable logging, ensure you have a tracing_subscriber configured in your application and set the RUST_LOG environment variable. For example:

```bash