MCP Server for LangGraph Agent

FastMCP-based Model Context Protocol server for ChatGPT Enterprise integration with LangGraph agent.

🎉 Quick Start

The fastest way to get started:

./start.sh

This will:

1. Check if your LangGraph agent is running on port 2024

2. Start the MCP server on port 8000

3. Start the test UI on port 3005

4. Open http://localhost:3005 in your browser

Overview

This MCP server provides a standardized interface to interact with a LangGraph agent deployed on port 2024, compliant with ChatGPT Enterprise integration requirements.

✨ Latest Updates

January 2025 - LangGraph CLI Integration

• ✅ Refactored to use LangGraph CLI API architecture

• ✅ Updated to /runs, /runs/stream, /ok endpoints

• ✅ Changed message format to {"type": "human"}

• ✅ Added 3 new tools: health check, agent status, thread listing

• ✅ Fixed all async operations (no more blocking calls)

• ✅ Updated web UI to match new API structure

See REFACTORING_SUMMARY.md for detailed changes.

Features

• ✅ MCP Protocol 2025-06-18 compliant

• ✅ ChatGPT Enterprise compatible (SSE transport)

• ✅ OAuth 2.0 Authentication - Google OAuth and API key support

• ✅ FastMCP 2.13.0+ framework for production-ready deployment

• ✅ LangGraph CLI API integration

• ✅ 6 Tools: invoke_agent, stream_agent, check_system_health, check_agent_status, get_thread_state, list_threads

• ✅ 2 Resources: Agent health check and server info

• ✅ Prompts: Formatted agent queries

• ✅ Web Test UI: Interactive testing interface on port 3005

• ✅ Secure by Default: Optional authentication for production deployments

Installation

1. Install dependencies:

pip install -r requirements.txt

2. Configure environment (optional):

# Copy example configuration
cp .env.example .env

# Edit .env with your settings
# For development without auth:
OAUTH_ENABLED=false

# For production with auth:
OAUTH_ENABLED=true
GOOGLE_CLIENT_ID=your-client-id
GOOGLE_CLIENT_SECRET=your-client-secret
API_KEYS=your-api-key-1,your-api-key-2

3. Generate credentials (if using OAuth):

python generate_credentials.py

See OAUTH_SETUP.md for detailed authentication setup.

Usage

Option 1: Quick Start Script (Recommended)

./start.sh

Option 2: Manual Start

Start MCP Server:

python src/agent_mcp/mcp_server.py

Start Test UI (optional):

cd web_ui && python server.py

Option 3: Using FastMCP CLI

python -m agent_mcp.mcp_server

Or using FastMCP CLI:

fastmcp run src/agent_mcp/mcp_server.py

For local development (STDIO):

fastmcp dev src/agent_mcp/mcp_server.py

Custom transport:

from agent_mcp.mcp_server import mcp

# HTTP transport
mcp.run(transport="http", host="0.0.0.0", port=8000, path="/mcp")

# SSE transport (for ChatGPT Enterprise)
mcp.run(transport="sse", host="0.0.0.0", port=8000)

Available Tools

1. invoke_agent

Execute a single invocation of the LangGraph agent.

{
    "prompt": "What is the capital of France?",
    "thread_id": "optional-thread-id"
}

2. stream_agent

Stream responses from the LangGraph agent.

{
    "prompt": "Tell me a story",
    "thread_id": "optional-thread-id"
}

3. get_agent_state

Retrieve the current state of a conversation thread.

{
    "thread_id": "thread-id-to-query"
}

Authentication

The MCP server supports three authentication methods for production deployments:

1. OAuth 2.0 (Google or Okta)

Enable user-based authentication with your preferred identity provider:

Google OAuth:

# .env configuration
OAUTH_ENABLED=true
OAUTH_PROVIDER=google
GOOGLE_CLIENT_ID=your-client-id.apps.googleusercontent.com
GOOGLE_CLIENT_SECRET=your-client-secret

Okta OAuth:

# .env configuration
OAUTH_ENABLED=true
OAUTH_PROVIDER=okta
OKTA_DOMAIN=your-domain.okta.com
OKTA_CLIENT_ID=your-okta-client-id
OKTA_CLIENT_SECRET=your-okta-client-secret

OAuth Endpoints:

• GET /auth/login - Initiate OAuth flow

• GET /auth/callback - OAuth callback handler

• GET /auth/logout - Logout

• GET /auth/status - Check authentication status

Quick Start Guides:

• Google OAuth Setup

• Okta OAuth Setup

2. API Key Authentication

Use API keys for service-to-service authentication:

# Generate API keys
python generate_credentials.py

# Add to .env
API_KEYS=key1,key2,key3

Using API Keys:

# cURL
curl -H "X-API-Key: your-api-key" http://localhost:8000/sse

# Python
headers = {"X-API-Key": "your-api-key"}

Testing Authentication

# Test OAuth setup
python test_oauth.py

# Or test manually
curl http://localhost:8000/health  # Public endpoint
curl -H "X-API-Key: your-key" http://localhost:8000/sse  # Protected

For detailed setup instructions, see OAUTH_SETUP.md

Resources

• agent://health - Agent health check

• agent://info - Agent capabilities and metadata

Prompts

• agent_query_prompt - Format queries for the agent

ChatGPT Enterprise Integration

This server is designed for ChatGPT Enterprise integration with:

1. SSE Transport: Default transport for real-time streaming

2. MCP Protocol 2025-06-18: Latest stable protocol version

3. Proper Tool Schemas: Auto-generated from Python type hints

4. Context Support: Logging and progress reporting

5. Error Handling: Comprehensive error responses

📚 Enterprise Apps & Connectors Documentation

Having trouble integrating with ChatGPT Enterprise "Apps & Connectors"?

We've created comprehensive documentation to help you:

• Start Here: Executive Summary - Quick overview of the issue and solutions

• Full Research Report - Detailed technical analysis

• Troubleshooting Checklist - Step-by-step diagnostic guide

• Code Fixes Guide - Ready-to-implement improvements

• Enterprise Admin Guide - For workspace administrators

• Visual Architecture Guide - Diagrams and flow charts

• Complete Documentation Index - All resources in one place

TL;DR: If your OpenAPI server works in Custom GPTs but not in Enterprise "Apps & Connectors", it's likely due to Enterprise workspace domain restrictions. Contact your Enterprise admin to whitelist mcp.marananapp.com in the GPT Actions settings.

ChatGPT Configuration

Add to your ChatGPT Enterprise MCP configuration:

{
  "mcpServers": {
    "langgraph-agent": {
      "url": "http://your-server:8000/sse",
      "transport": "sse"
    }
  }
}

Testing

Web UI Test Tool

We provide a beautiful web-based UI to test your MCP server and LangGraph agent:

# Start the test UI server
cd web_ui
python server.py

Then open http://localhost:3005 in your browser to:

• Test MCP server connectivity

• Test LangGraph agent connectivity

• Invoke agent with custom prompts

• Stream responses in real-time

• View activity logs

See web_ui/README.md for details.

Unit Tests

Run tests:

pytest tests/test_mcp_server.py -v

Run all tests:

pytest

Development

Project Structure

agent-mcp-py/
├── src/
│   └── agent_mcp/
│       ├── __init__.py
│       └── mcp_server.py      # FastMCP server implementation
├── tests/
│   ├── test_mcp_server.py     # MCP server tests
│   └── test_*.py              # Other tests
├── requirements.txt           # Production dependencies
├── requirements-dev.txt       # Development dependencies
└── README.md

Adding New Tools

from fastmcp import Context

@mcp.tool()
async def my_tool(param: str, ctx: Context = None) -> dict:
    """Tool description for ChatGPT."""
    if ctx:
        await ctx.info(f"Processing: {param}")

    # Your logic here
    return {"result": "success"}

Adding Resources

@mcp.resource("custom://resource")
async def my_resource() -> str:
    """Resource description."""
    return "Resource content"

Architecture

┌─────────────────┐
│  ChatGPT        │
│  Enterprise     │
└────────┬────────┘
         │ MCP/SSE
         │
┌────────▼────────┐
│  FastMCP        │
│  Server         │
│  (Port 8000)    │
└────────┬────────┘
         │ HTTP
         │
┌────────▼────────┐
│  LangGraph      │
│  Agent          │
│  (Port 2024)    │
└─────────────────┘

Production Deployment

With Authentication

from fastmcp.server.auth.providers.google import GoogleProvider

auth = GoogleProvider(
    client_id="your-client-id",
    client_secret="your-client-secret",
    base_url="https://your-domain.com"
)

mcp = FastMCP(
    "LangGraph Agent Server",
    auth=auth
)

Docker Deployment

FROM python:3.11-slim

WORKDIR /app
COPY requirements.txt .
RUN pip install -r requirements.txt

COPY src/ ./src/
CMD ["python", "-m", "agent_mcp.mcp_server"]

License

MIT

References

• FastMCP Documentation

• MCP Specification

• ChatGPT Enterprise