mcp_server/
├── src/
│   ├── index.ts                    # Entry point
│   ├── core/
│   │   ├── tool-registry.ts        # Tool registry
│   │   ├── tool-loader.ts          # Dynamic tool loader
│   │   └── tool-executor.ts        # Isolated executor (timeout + error handling)
│   ├── server/
│   │   ├── app.ts                  # Express + StreamableHTTP
│   │   └── mcp-server.ts           # MCP Server instance
│   ├── middleware/
│   │   └── auth.ts                 # Bearer token authentication
│   ├── tools/                      # Loosely coupled tools directory
│   │   ├── calculator/index.ts     # Calculator tool (add/subtract/multiply/divide)
│   │   ├── echo/index.ts           # Echo tool (echo/reverse/info)
│   │   └── time/index.ts           # Time tool (get_current_time/convert_time/format_time)
│   ├── types/mcp.ts                # Type definitions
│   └── utils/logger.ts             # Terminal logger
├── Dockerfile                      # Multi-stage build
├── docker-compose.yml
├── package.json
└── tsconfig.json

# Install dependencies
npm install

# Create .env file
echo "AUTHORIZATION_KEY=your-secret-key" > .env

# Start development server
npm run dev

# Build and run with docker-compose
docker-compose up -d --build

# Or build manually
docker build -t mcp-server .
docker run -e AUTHORIZATION_KEY=your-secret-key -p 3000:3000 mcp-server

2 + 3 * 4        → 14
(2 + 3) * 4      → 20
2^10             → 1024
sqrt(16)         → 4
2 * pi           → 6.283...
sin(0)           → 0
pow(2, 8)        → 256
17 // 5          → 3
17 % 5           → 2

{
  "mcpServers": {
    "calculator": {
      "url": "http://localhost:3000/mcp/calculator",
      "transport": "streamable-http",
      "headers": {
        "Authorization": "Bearer your-secret-key"
      }
    },
    "time": {
      "url": "http://localhost:3000/mcp/time",
      "transport": "streamable-http",
      "headers": {
        "Authorization": "Bearer your-secret-key"
      }
    }
  }
}

{
  "mcpServers": {
    "calculator": {
      "url": "http://localhost:3000/mcp/calculator",
      "transport": "streamable-http",
      "headers": {
        "Authorization": "Bearer your-secret-key"
      }
    }
  }
}

import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";

const client = new Client({
  name: "my-client",
  version: "1.0.0",
});

const transport = new StreamableHTTPClientTransport(
  new URL("http://localhost:3000/mcp/calculator"),
  {
    requestInit: {
      headers: {
        Authorization: "Bearer your-secret-key",
      },
    },
  }
);

await client.connect(transport);

// List available tools
const tools = await client.listTools();
console.log(tools);

// Call a tool
const result = await client.callTool({
  name: "add",
  arguments: { a: 10, b: 5 },
});
console.log(result);

src/tools/my-tool/
└── index.ts

import { z } from "zod";
import { MCPTool, MCPMethodDefinition } from "../../types/mcp.js";

const myTool: MCPTool = {
  name: "my-tool",
  description: "Description of my tool",
  version: "1.0.0",

  getMethods(): MCPMethodDefinition[] {
    return [
      {
        name: "my-method",
        description: "Description of my method",
        inputSchema: {
          param1: z.string().describe("Parameter description"),
        },
        handler: async (params) => {
          const { param1 } = params as { param1: string };
          return { result: param1 };
        },
      },
    ];
  },

  async initialize() {
    // Initialization logic
  },

  async healthCheck() {
    return true;
  },
};

export default myTool;

npm run dev        # Start development server with hot reload
npm run build      # Build for production
npm start          # Start production server
npm test           # Run tests
npm run lint       # Check code style
npm run lint:fix   # Auto-fix code style issues