MCP Client (Claude, VS Code, etc.)
        │
        │  HTTP POST /mcp  (JSON-RPC 2.0)
        ▼
  Express.js server  :3000
        │
        │  per-request lifecycle
        ▼
  McpServer  ──  StreamableHTTPServerTransport
        │
  4 calculation tools

npm install

npm run dev

# Option A — update start script to match tsconfig outDir
npm run build
node build/index.js

# Option B — update tsconfig outDir to "dist" and then run
npm run build
npm start

docker build -t mcp-calculation .
docker run -p 3000:3000 mcp-calculation

docker run -p 8080:8080 -e PORT=8080 mcp-calculation

{
  "servers": {
    "my-mcp-server-de2625e8": {
      "url": "http://localhost:3000/mcp",
      "type": "http"
    }
  }
}

{
  "mcpServers": {
    "calculation-server": {
      "url": "http://localhost:3000/mcp",
      "type": "http"
    }
  }
}

What is 42 plus 58?
What is 100 divided by 4?
Multiply 7 by 8.
Subtract 15 from 100.

# List available tools
curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/list"
  }'

# Call add_two_numbers
curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 2,
    "method": "tools/call",
    "params": {
      "name": "add_two_numbers",
      "arguments": { "a": 12, "b": 30 }
    }
  }'

{
  "jsonrpc": "2.0",
  "id": 2,
  "result": {
    "content": [{ "type": "text", "text": "The sum of 12 and 30 is 42" }],
    "structuredContent": { "result": 42 }
  }
}

# Division by zero — returns an error response (not an HTTP error)
curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 3,
    "method": "tools/call",
    "params": {
      "name": "divide_two_numbers",
      "arguments": { "a": 10, "b": 0 }
    }
  }'

mcp-calculation/
├── src/
│   └── index.ts        # Server entry point — tools + Express setup
├── .vscode/
│   └── mcp.json        # VS Code MCP client config
├── Dockerfile
├── package.json
└── tsconfig.json