What is Sam Serverless Mcp Server

sam-serverless-mcp-server is a minimal Model Context Protocol (MCP) server that is deployed on AWS Lambda and exposed via Amazon API Gateway. It is built using the Serverless Application Model (SAM) and integrates with AWS Lambda functions through a middleware developed by Frédéric Barthelet.

Use cases

Use cases for sam-serverless-mcp-server include building serverless applications that require context management, integrating with other AWS services through APIs, and developing and testing MCP-based applications locally.

How to use

To use sam-serverless-mcp-server, first install the necessary dependencies with ‘npm install’. Then, you can run the server locally using the command ‘sam local start-api’, which will expose the HTTP POST endpoint at ‘/mcp’.

Key features

Key features include a minimal MCP server setup using @modelcontextprotocol/sdk, deployment as a single AWS Lambda function, an HTTP POST endpoint via API Gateway, support for local development with SAM, and a simple example tool for JSON-RPC interaction.

Where to use

sam-serverless-mcp-server can be used in various fields such as serverless application development, API integration, and any scenario requiring a lightweight MCP server for handling model context.

🧠 sam-serverless-mcp-server

A super simple Model Context Protocol (MCP) server deployed on AWS Lambda and exposed via Amazon API Gateway, deployed with Serverless Application Model (SAM).
This skeleton is based on the awesome work of Frédéric Barthelet: which has developed a middy middleware for Model Context Protocol (MCP) server integration with AWS Lambda functions in this repo

Long story

📖 Read the article of this series here on dev.to

🛠 Features

• 🪄 Minimal MCP server setup using @modelcontextprotocol/sdk
• 🚀 Deployed as a single AWS Lambda function
• 🌐 HTTP POST endpoint exposed via API Gateway at /mcp
• 🔄 Supports local development via SAM
• 🧪 Includes a simple example tool (add) with JSON-RPC interaction

📦 Project Structure

sam-serverless-mcp-server/
├── __tests__/              # Jest tests
├── src/                    # Source code
│   └── index.js                # MCP server handler
├── .gitignore              # Git ignore file
├── buildspec.yml           # Buildspec file for AWS CodeBuild and CodePipeline (CI/CD)
├── jest.config.mjs         # Jest config file
├── package.json            # Project dependencies
├── package-lock.json       # Project lock file
├── README.md               # This documentation file
├── samconfig.toml          # Serverless Application Model config
└── template.yml            # Serverless Application Model template

🛠 Prerequisites

• Node.js v22+
• Docker
• AWS CLI
• SAM CLI

🚀 Getting Started

1. Install dependencies:

npm install

2. Run Locally with SAM

sam local start-api

Local endpoint will be available at:
POST http://localhost:3000/mcp

Switch to Api Gateway V2 (HTTP API)

If you want to use API Gateway V2, you can change the template.yml file to use HttpApi instead of Api in the Events section. This will allow you to use HTTP APIs instead of REST APIs.
This will allow you to use HTTP APIs instead of REST APIs.

Events:
  McpHttpApi:
    Type: HttpApi  # 👈 This switches to HTTP API (v2)
    Properties:
      Path: /mcp
      Method: POST

🧪 Test with curl requests

List tools

curl --location 'http://localhost:3000/mcp' \
--header 'content-type: application/json' \
--header 'accept: application/json' \
--header 'jsonrpc: 2.0' \
--data '{
  "jsonrpc": "2.0",
  "method": "tools/list",
  "id": 1
}'

➕ Use the add Tool

curl --location 'http://localhost:3000/mcp' \
--header 'content-type: application/json' \
--header 'accept: application/json' \
--header 'jsonrpc: 2.0' \
--data '{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "add",
    "arguments": {
      "a": 5,
      "b": 3
    }
  }
}'

🧪 Test with jest

There are some basic tests included in the __tests__ folder. You can run them with:

npm run test

🧬 Code Breakdown

This code is based on the awesome work of Frédéric Barthelet: which has developed a middy middleware for Model Context Protocol (MCP) server integration with AWS Lambda functions in this repo

src/index.js

import middy from "@middy/core";
import httpErrorHandler from "@middy/http-error-handler";
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";
import mcpMiddleware from "middy-mcp";

const server = new McpServer({
  name: "Lambda hosted MCP Server",
  version: "1.0.0",
});

server.tool("add", { a: z.number(), b: z.number() }, async ({ a, b }) => ({
  content: [{ type: "text", text: String(a + b) }],
}));

export const handler = middy()
  .use(mcpMiddleware({ server }))
  .use(httpErrorHandler());

📡 Deploy to AWS

Just run:

sam build
sam deploy --guided

After deployment, the MCP server will be live at the URL output by the command.

📘 License

MIT — feel free to fork, tweak, and deploy your own version!