MCP Servers in 2026:
The Complete Guide to AI Agent Tool Integration

npm init -y && npm install @modelcontextprotocol/sdk zod

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

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

// Define a tool with typed parameters
server.tool(
  "get_weather",
  "Get current weather for a city",
  {
    city: z.string().describe("City name"),
    units: z.enum(["celsius", "fahrenheit"]).default("celsius"),
  },
  async ({ city, units }) => {
    // Your implementation here
    const temp = units === "celsius" ? "22C" : "72F";
    return {
      content: [
        {
          type: "text",
          text: `Weather in ${city}: ${temp}, partly cloudy`,
        },
      ],
    };
  }
);

// Define a resource
server.resource(
  "config",
  "config://app",
  async (uri) => ({
    contents: [
      {
        uri: uri.href,
        mimeType: "application/json",
        text: JSON.stringify({ version: "1.0", debug: false }),
      },
    ],
  })
);

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

{
  "mcpServers": {
    "my-custom-server": {
      "command": "npx",
      "args": ["tsx", "server.ts"]
    }
  }
}