MCP Lambda SAM

What is MCP Lambda SAM?

MCP Lambda SAM is a serverless implementation of the Model Context Protocol (MCP) using AWS Lambda and the Serverless Application Model (SAM). It provides two interfaces: an administrative interface for registering MCP tools, resources, and prompts, and a client interface for establishing SSE connections, sending commands, and receiving streaming responses.

How to use MCP Lambda SAM?

Deploy via npx @markvp/mcp-lambda-sam deploy, the AWS Serverless Application Repository, or programmatic install. After deployment, administrators register tools through a dedicated Lambda function URL with IAM authentication. Clients connect using AWS Signature V4 signed SSE requests, obtain a session ID, and then send JSON-RPC commands to the message endpoint.

Key features of MCP Lambda SAM

• Serverless MCP implementation using AWS Lambda and SAM
• Two interfaces: system administration and client usage
• SSE streaming for real-time communication
• DynamoDB tables for session and registration persistence
• IAM-based authentication via Lambda Function URLs
• Supports registration, update, deletion, and listing of tools/resources/prompts
• Deploy via npx CLI, SAR, or local SAM commands

Use cases of MCP Lambda SAM

• Administrators registering new MCP tools, resources, or prompts via the registration API
• Clients establishing SSE connections to receive streaming responses from registered tools
• Managing multiple server instances by providing different stack names
• Deploying in a VPC for secure internal access

FAQ from MCP Lambda SAM

What are the runtime requirements?

AWS CLI, AWS SAM CLI, Node.js 20.x or later, and an AWS account with permissions to create Lambda functions, DynamoDB tables, IAM roles, and SQS queues.

How do I deploy MCP Lambda SAM?

You can deploy using npx @markvp/mcp-lambda-sam deploy, from the AWS Serverless Application Repository (search “mcp-lambda-sam”), programmatically by installing the npm package, or locally with sam build and sam deploy --guided.

How does authentication work?

All MCP endpoints are IAM-protected via Lambda Function URLs with AWS_IAM auth type. Administrators need permission to invoke the registration function URL; clients need permission to invoke the MCP function URL. Permissions are granted using IAM policies or aws lambda add-permission commands.

How do I register a tool or resource?

Send an HTTP POST request to the registration function URL with JSON body containing type, name, description, lambdaArn, and parameters. Use awscurl or any client capable of AWS Signature V4 signing.

What common errors can occur?

401 (invalid/missing credentials), 403 (insufficient permissions), 404 (invalid session ID), and 429 (rate limit exceeded). Troubleshooting includes verifying credentials, IAM permissions, session ID validity, and command format.