# MCP Builder > Build MCP (Model Context Protocol) servers that give Claude new capabilities. Use when user wants to create an MCP server, add tools to Claude, or integrate external services. Use when this capability is needed. - Skill: `tomevault-io/mcp-builder-54` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/mcp-builder-54` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/mcp-builder-54/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/mcp-builder-54 --- # MCP Server Building Skill You now have expertise in building MCP (Model Context Protocol) servers. MCP enables Claude to interact with external services through a standardized protocol. ## What is MCP? MCP servers expose: - **Tools**: Functions Claude can call (like API endpoints) - **Resources**: Data Claude can read (like files or database records) - **Prompts**: Pre-built prompt templates ## Quick Start: TypeScript MCP Server ### 1. Project Setup ```bash # Create project mkdir my-mcp-server && cd my-mcp-server # Install MCP SDK npm init -y npm install @modelcontextprotocol/sdk npm install -D typescript tsx @types/node ``` ### 2. Basic Server Template ```typescript // src/server.ts - A simple MCP server import { Server } from "@modelcontextprotocol/sdk/server/index.js"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; const server = new Server({ name: "my-server", version: "1.0.0" }); server.setRequestHandler("tools/list", async () => ({ tools: [ { name: "hello", description: "Say hello to someone", inputSchema: { type: "object", properties: { name: { type: "string" } }, required: ["name"], }, }, { name: "add_numbers", description: "Add two numbers together", inputSchema: { type: "object", properties: { a: { type: "number" }, b: { type: "number" } }, required: ["a", "b"], }, }, ], })); server.setRequestHandler("tools/call", async (request) => { const args = request.params.arguments as Record; if (request.params.name === "hello") { return { content: [{ type: "text", text: `Hello, ${args.name}!` }] }; } if (request.params.name === "add_numbers") { return { content: [{ type: "text", text: String(Number(args.a) + Number(args.b)) }] }; } throw new Error(`Unknown tool: ${request.params.name}`); }); await server.connect(new StdioServerTransport()); ``` ### 3. Register with Claude Add to `~/.claude/mcp.json`: ```json { "mcpServers": { "my-server": { "command": "node", "args": ["/path/to/dist/server.js"] } } } ``` ## TypeScript MCP Server ### 1. Setup ```bash mkdir my-mcp-server && cd my-mcp-server npm init -y npm install @modelcontextprotocol/sdk ``` ### 2. Template ```typescript // src/index.ts import { Server } from "@modelcontextprotocol/sdk/server/index.js"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; const server = new Server({ name: "my-server", version: "1.0.0", }); // Define tools server.setRequestHandler("tools/list", async () => ({ tools: [ { name: "hello", description: "Say hello to someone", inputSchema: { type: "object", properties: { name: { type: "string", description: "Name to greet" }, }, required: ["name"], }, }, ], })); server.setRequestHandler("tools/call", async (request) => { if (request.params.name === "hello") { const name = request.params.arguments.name; return { content: [{ type: "text", text: `Hello, ${name}!` }] }; } throw new Error("Unknown tool"); }); // Start server const transport = new StdioServerTransport(); server.connect(transport); ``` ## Advanced Patterns ### External API Integration ```typescript server.setRequestHandler("tools/call", async (request) => { if (request.params.name !== "get_weather") throw new Error("Unknown tool"); const { city } = request.params.arguments as { city: string }; const url = new URL("https://api.weatherapi.com/v1/current.json"); url.searchParams.set("key", "YOUR_API_KEY"); url.searchParams.set("q", city); const response = await fetch(url); const data = await response.json() as { current: { temp_c: number; condition: { text: string } }; }; return { content: [{ type: "text", text: `${city}: ${data.current.temp_c}C, ${data.current.condition.text}` }], }; }); ``` ### Database Access ```typescript import Database from "better-sqlite3"; server.setRequestHandler("tools/call", async (request) => { if (request.params.name !== "query_db") throw new Error("Unknown tool"); const { sql } = request.params.arguments as { sql: string }; if (!sql.trim().toUpperCase().startsWith("SELECT")) { return { content: [{ type: "text", text: "Error: Only SELECT queries allowed" }] }; } const db = new Database("data.db", { readonly: true }); const rows = db.prepare(sql).all(); db.close(); return { content: [{ type: "text", text: JSON.stringify(rows) }] }; }); ``` ### Resources (Read-only Data) ```typescript import { readFile } from "node:fs/promises"; server.setRequestHandler("resources/read", async (request) => { if (request.params.uri === "config://settings") { return { contents: [{ uri: request.params.uri, mimeType: "application/json", text: await readFile("settings.json", "utf8") }], }; } throw new Error(`Unknown resource: ${request.params.uri}`); }); ``` ## Testing ```bash # Test with MCP Inspector npx @modelcontextprotocol/inspector node dist/server.js # Or send test messages directly echo '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | node dist/server.js ``` ## Best Practices 1. **Clear tool descriptions**: Claude uses these to decide when to call tools 2. **Input validation**: Always validate and sanitize inputs 3. **Error handling**: Return meaningful error messages 4. **Async by default**: Use async/await for I/O operations 5. **Security**: Never expose sensitive operations without auth 6. **Idempotency**: Tools should be safe to retry --- > Source: [zzjzz9266a/learn-claude-code-ts](https://github.com/zzjzz9266a/learn-claude-code-ts) — distributed by [TomeVault](https://tomevault.io).