Rust MCP SDK

Everything you need for MCP in Rust

🎯

100% Conformance

Passes all server and client MCP conformance tests - protocol version 2025-11-25.

🔌

All Transports

Stdio, Streamable HTTP, and backward-compatible SSE. One handler works across all transports.

🧩

Framework Agnostic

Native Axum and Actix-web integrations, plus BYO-server mode for existing apps.

🏭

Production Ready

DNS rebinding protection, resumability, health checks, OAuth 2.1, and MCP Tasks.

✨

Powerful Macros

mcp_tool, tool_box!, mcp_elicit - generate MCP schemas directly from your Rust structs.

🦀

Open & Free

MIT licensed. Part of the rust-mcp-stack ecosystem with rust-mcp-filesystem and mcp-discovery.

Build an MCP server in 3 steps

use async_trait::async_trait;
use rust_mcp_sdk::*;
use std::sync::Arc;

// Step 1 - Define a tool
#[macros::mcp_tool(name = "say_hello", description = "Returns a friendly greeting")]
#[derive(Debug, serde::Deserialize, serde::Serialize, macros::JsonSchema)]
pub struct SayHelloTool { pub name: String }

// Step 2 - Implement the handler
#[async_trait]
impl ServerHandler for MyServer {
    async fn handle_list_tools_request(
        &self, _: Option<PaginatedRequestParams>, _: Arc<dyn McpServer>,
    ) -> Result<ListToolsResult, RpcError> {
        Ok(ListToolsResult { tools: vec![SayHelloTool::tool()], ..Default::default() })
    }

    async fn handle_call_tool_request(
        &self, params: CallToolRequestParams, _: Arc<dyn McpServer>,
    ) -> Result<CallToolResult, CallToolError> {
        let input: SayHelloTool = params.arguments.parse()?;
        Ok(CallToolResult::text_content(vec![format!("Hello, {}!", input.name)]))
    }
}

// Step 3 - Start the server
#[tokio::main]
async fn main() -> SdkResult<()> {
    let server = server_runtime::create_server(McpServerOptions {
        transport: StdioTransport::new(TransportOptions::default()?)?,
        handler: MyServer.to_mcp_server_handler(),
        ..Default::default()
    });
    server.start().await
}