OpenAPI MCP Server - AWS Lambda Deployment

Serverless deployment of the AWS Labs OpenAPI MCP Server on AWS Lambda with API Gateway.

Overview

This project wraps the awslabs openapi-mcp-server to run as a serverless Lambda function, enabling MCP (Model Context Protocol) clients to interact with OpenAPI-defined APIs through AWS infrastructure.

Architecture

Lambda Function: FastMCP server with HTTP transport (Starlette ASGI)
API Gateway: HTTP API exposing the MCP endpoints
Transport: Mangum ASGI adapter (no child process overhead)

Prerequisites

Python 3.12+
uv package manager
AWS CLI configured
AWS CDK CLI: npm install -g aws-cdk

Local Setup

Install dependencies:

uv sync

Deployment

1. Bootstrap CDK (first time only)

cdk bootstrap

2. Deploy Stack

cd cdk cdk deploy \ --parameters ApiName=MyAPI \ --parameters ApiBaseUrl=https://api.example.com \ --parameters ApiSpecUrl=https://api.example.com/openapi.json \ --parameters AuthType=none

Configuration Parameters

ApiName: Display name for the API
ApiBaseUrl: Base URL of the target API
ApiSpecUrl: URL to the OpenAPI specification (JSON or YAML)
AuthType: Authentication method (none, basic, bearer, api_key, cognito)

Additional Auth Configuration

Set environment variables in cdk/openapi_mcp_stack.py for authentication:

Basic Auth:

AUTH_USERNAME
AUTH_PASSWORD

Bearer Token:

AUTH_TOKEN

API Key:

AUTH_API_KEY
AUTH_API_KEY_NAME
AUTH_API_KEY_IN (header/query/cookie)

Cognito:

AUTH_COGNITO_CLIENT_ID
AUTH_COGNITO_USERNAME
AUTH_COGNITO_PASSWORD
AUTH_COGNITO_USER_POOL_ID
AUTH_COGNITO_REGION

3. Get API URL

After deployment, CDK outputs the API Gateway URL:

# Output example: # OpenApiMcpStack.ApiUrl = https://abc123.execute-api.us-east-1.amazonaws.com/

Testing

Test the deployed Lambda function:

curl -X POST https://<api-url>/message \ -H "Content-Type: application/json" \ -d '{"jsonrpc": "2.0", "method": "tools/list", "id": 1}'

Performance Considerations

Cold Start: ~1-2 seconds (initializes MCP server + loads OpenAPI spec)
Warm Start: ~100-300ms (reuses server instance)
Timeout: 30 seconds (configurable in stack)
Memory: 512 MB (configurable in stack)

Cost Optimization

Requests: Pay per invocation
Memory/Duration: 512 MB x execution time
API Gateway: HTTP API (cheaper than REST API)

Development

Run MCP server locally:

uv run awslabs.openapi-mcp-server \ --api-name MyAPI \ --api-url https://api.example.com \ --spec-url https://api.example.com/openapi.json

Cleanup

cd cdk cdk destroy

License

This project includes code from awslabs/mcp licensed under Apache-2.0. See LICENSE and NOTICE files.

This server cannot be installed

-

security - not tested

A

license - permissive license

-

quality - not tested

How are these scores calculated?

remote-capable server

The server can be hosted and run remotely because it primarily relies on remote services or has no dependency on the local environment.

Enables MCP clients to interact with any OpenAPI-defined REST API through a serverless AWS Lambda deployment. Supports multiple authentication methods and provides cost-effective, scalable access to third-party APIs through natural language.

OpenAPI Lambda MCP Server