mcpsdk

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description: MCP Server Implementation Guide: Tools in TypeScript globs: *.ts alwaysApply: false

MCP Server Implementation Guide: Tools in TypeScript

This guide provides a concise overview of how to implement an Anthropic Model Context Protocol (MCP) server that offers tools in TypeScript. It focuses specifically on the core aspects needed to create a functional MCP server without diving into general TypeScript project setup.

Core Concepts

The Model Context Protocol (MCP) is an open standard that allows AI assistants like Claude to interact with external systems through standardized interfaces. An MCP server can expose:

• Resources: Read-only data (similar to GET endpoints)
• Tools: Functions that perform actions (similar to POST endpoints)
• Prompts: Reusable templates for AI interactions

This guide focuses specifically on implementing Tools.

Basic MCP Server Structure

Here's the minimal structure for an MCP server that provides tools:

import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import {
  CallToolRequestSchema,
  ListToolsRequestSchema,
  ToolSchema,
} from "@modelcontextprotocol/sdk/types.js";
import { z } from "zod"; // For input validation
import { zodToJsonSchema } from "zod-to-json-schema";

// Define server with metadata
const server = new Server(
  {
    name: "my-tool-server",
    version: "1.0.0",
  },
  {
    capabilities: {
      tools: {}, // Indicates we'll provide tools
    },
  }
);

// Start the server with stdio transport
async function runServer() {
  const transport = new StdioServerTransport();
  await server.connect(transport);
  console.error("MCP server running on stdio");
}

runServer().catch((error) => {
  console.error("Fatal error running server:", error);
  process.exit(1);
});

Implementing Tools

There are two key request handlers you need to implement for tools:

1. ListToolsRequestSchema: Advertises available tools and their schemas
2. CallToolRequestSchema: Handles actual tool invocations