When a pre-built server doesn't exist for your use case, building one is straightforward with the official SDKs.

MCP Server SDK Options

• TypeScript SDK — @modelcontextprotocol/sdk (most popular)
• Python SDK — mcp package
• Rust, Go, Java — Community SDKs available

Basic TypeScript MCP Server

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";

const server = new McpServer({
  name: "my-custom-server",
  version: "1.0.0",
});

// Define a tool
server.tool(
  "get_weather",
  "Get current weather for a city",
  {
    city: { type: "string", description: "City name" },
  },
  async ({ city }) => {
    const response = await fetch(
      \`https://api.weather.com/v1/current?city=\${city}\`
    );
    const data = await response.json();
    return {
      content: [{ type: "text", text: JSON.stringify(data) }],
    };
  }
);

// Connect via stdio transport
const transport = new StdioServerTransport();
await server.connect(transport);

Defining Tools

Every tool needs:

• Name — A clear, descriptive function name
• Description — What the tool does (the AI reads this to decide when to use it)
• Parameters — Input schema with types and descriptions
• Handler — The function that executes when called

Defining Resources

Resources expose data for the AI to read:

server.resource(
  "config",
  "application://config",
  async () => ({
    contents: [{
      uri: "application://config",
      text: JSON.stringify(appConfig),
      mimeType: "application/json",
    }],
  })
);

Testing Your Server

• Use the MCP Inspector tool to test servers interactively
• Connect to Claude Desktop and verify tools appear
• Test edge cases: invalid inputs, API failures, timeouts
• Monitor logs for errors during tool execution

Deployment Options

• Local — Run on your machine for personal tools (stdio transport)
• SSE (Server-Sent Events) — Run as a web service for remote access
• Docker — Containerize for consistent deployment
• Cloud functions — Deploy individual tools as serverless functions