Dexcom API MCP Servers

This repository contains three different MCP (Model Context Protocol) server implementations for the Dexcom API:

1. stdio - Command-line based server using stdio transport
2. SSE - Web-based server using Server-Sent Events transport
3. streamableHttp - Web-based server using StreamableHTTP transport

Each server provides the same Dexcom API tools but with different transport mechanisms.

Quick Start

The easiest way to get started is to use the unified commands from the root directory:

# Install all dependencies
npm install

# Build all servers
npm run build:all

# Start the SSE web server (recommended for first-time users)
npm run start:sse

Then open http://localhost:3000 in your browser and follow the authentication flow.

Authentication

All servers require authentication with the Dexcom API using OAuth2. You'll need to:

1. Register an application with Dexcom to get client credentials
2. Configure your server with these credentials
3. Authenticate with Dexcom to get an access token

Registering with Dexcom

1. Visit the Dexcom Developer Portal
2. Create an account and register a new application
3. Note your Client ID and Client Secret

Configuration

Each server uses a .env file for configuration. When you first run a server, it will automatically create a .env file from the .env.example template if one doesn't exist.

Edit the .env file in the server directory you want to use and add your Dexcom credentials:

OAUTH_CLIENT_ID_BEARERAUTH=your_client_id_here
OAUTH_CLIENT_SECRET_BEARERAUTH=your_client_secret_here
OAUTH_REDIRECT_URI=http://localhost:3000/auth/callback

Using ngrok for Local Development

When developing locally, you'll need a publicly accessible URL for the OAuth callback. You can use ngrok to create a secure tunnel to your local server:

1. Download and install ngrok
2. Start your server (e.g., npm run start:sse)
3. In a separate terminal, start ngrok:

ngrok http 3000

4. Copy the HTTPS URL provided by ngrok (e.g., https://a1b2c3d4.ngrok.io)
5. Update your .env file with the ngrok URL:

OAUTH_REDIRECT_URI=https://a1b2c3d4.ngrok.io/auth/callback

6. Update your application in the Dexcom Developer Portal to include this redirect URI
7. Restart your server to apply the changes

This allows Dexcom to redirect back to your local development server after authentication.

Server-Specific Usage

stdio Server

The stdio server runs in the command line and uses a CLI-based OAuth flow:

# Run the authentication flow
npm run auth:stdio

# Start the server
npm run start:stdio

# For development with auto-reload
npm run dev:stdio

SSE Server

The SSE server provides a web interface with built-in OAuth flow:

# Start the server
npm run start:sse

# For development with auto-reload
npm run dev:sse

Open http://localhost:3000 in your browser, click "Login with Dexcom" and follow the authentication flow.

StreamableHTTP Server

The StreamableHTTP server also provides a web interface with built-in OAuth flow:

# Start the server
npm run start:http

# For development with auto-reload
npm run dev:http

Open http://localhost:3000 in your browser, click "Login with Dexcom" and follow the authentication flow.

Available Tools

All servers provide the following Dexcom API tools:

• getdatarange - Get the available data range
• userauthorization - Get user authorization
• exchangeauthorizationcode - Exchange authorization code for token
• getalerts - Get alerts
• getcalibrations - Get calibrations
• getestimatedglucosevalues - Get estimated glucose values

Using the Tools

Web Interface (SSE and StreamableHTTP)

1. Log in with Dexcom using the "Login with Dexcom" button
2. Enter commands in the format: toolName param1=value1 param2=value2

Example:

getdatarange

getestimatedglucosevalues startDate=2023-01-01T00:00:00Z endDate=2023-01-02T00:00:00Z

Command Line (stdio)

After starting the stdio server, enter commands in the same format:

getdatarange

Token Management

OAuth tokens are automatically cached and refreshed when needed. The tokens are stored in:

• stdio: stdio/data/token.json
• SSE: sse/data/token.json
• StreamableHTTP: streamableHttp/data/token.json

Development

This project uses a workspace structure to manage the three server implementations. Common code is shared in the shared directory.

Project Structure

dexcom-api-mcp-servers/
├── shared/              # Shared utilities and configuration
├── stdio/               # Command-line server
├── sse/                 # Server-Sent Events web server
├── streamableHttp/      # StreamableHTTP web server
└── package.json         # Root workspace configuration

Development Workflow

1. Make changes to the code
2. Run the appropriate dev script for auto-reloading:
   • npm run dev:stdio for stdio server
   • npm run dev:sse for SSE server
   • npm run dev:http for StreamableHTTP server

Building

To build all servers:

npm run build:all

Troubleshooting

Authentication Issues

• Ensure your Dexcom Client ID and Secret are correct in the .env file
• Check that your redirect URI matches what's registered in the Dexcom Developer Portal
• If tokens expire, the servers will automatically refresh them if possible
• When using ngrok, make sure to update both your .env file and the Dexcom Developer Portal with the new ngrok URL each time you restart ngrok

Connection Issues

• For web servers, ensure port 3000 is available (or change PORT in .env)
• For stdio server, check the console output for any error messages

Data Issues

• Verify the date ranges you're requesting contain data
• Ensure your Dexcom account has access to the requested data

Attributions

Dexcom OpenAPI spec Thanks to rockybranches! OpenAPI to MCP generator Thanks to harsha-iiiv for a quick and easy solution!