Lambda MCP Server (TypeScript + AWS SAM)

This project implements an MCP-style JSON-RPC endpoint on AWS Lambda using TypeScript and Node.js, deployed with AWS SAM.

The Lambda supports:

• initialize
• tools/list
• tools/call

The goal is to expose MCP functions as Lambda-executed tools over an HTTP API endpoint.

Current integration tool (public API):

• weather_forecast (Open-Meteo API)

Project Structure

• template.yaml: AWS SAM template.
• src/handler.ts: Lambda handler with MCP method routing and tool execution.
• src/use-cases/initialize.ts: initialize operation logic.
• src/use-cases/tools-list.ts: tools/list operation logic.
• src/use-cases/tools-call.ts: tools/call operation logic.
• events/*.json: test events for local invocation.
• docs/lambda-mcp-article.md: English article about using Lambda for MCP functions.

Prerequisites

• Node.js 20+
• AWS SAM CLI
• AWS credentials configured (aws configure)

Install

npm install

Local Validation

npm run tsc
npm run validate

Local Invocation

sam local invoke McpFunction --event events/initialize.json
sam local invoke McpFunction --event events/tools-list.json
sam local invoke McpFunction --event events/tools-call-weather.json

Or run as local API:

sam local start-api

Then send requests:

curl -X POST http://127.0.0.1:3000/mcp \
  -H "content-type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}'

Deploy

sam build
sam deploy --guided --profile nome-do-seu-profile

After deployment, use the McpApiUrl output as your MCP HTTP endpoint.