Langgraph Multiagent Boilerplate

LangGraph Multi-Agent Boilerplate

A robust boilerplate for building AI agent clusters efficiently using LangGraph with supervisor architecture, Model Context Protocol (MCP) integration, and comprehensive API.

🌟 Features

• Multi-Agent Architecture: Build AI agent clusters with supervisor coordination
• LangGraph Integration: Leverage LangGraph's powerful state management for agent workflows
• MCP Support: Integrate tools via Model Context Protocol servers
• Streaming API: Real-time streaming responses for interactive conversations
• Database Persistence: Store conversations, agent states, and activity logs in PostgreSQL
• Cloud Storage: File management with Cloudflare R2
• Comprehensive API: RESTful endpoints with FastAPI, including Swagger documentation
• Security: Authentication middleware, error handling, and security best practices

🚀 Getting Started

Prerequisites

• Python 3.10+
• PostgreSQL
• Cloudflare R2 account (optional, for cloud storage)
• OpenRouter AI API key (or other compatible AI provider)

Installation

1. Clone the repository

git clone https://github.com/yourusername/langgraph-multiagent-boilerplate.git
cd langgraph-multiagent-boilerplate

1. Set up a Python virtual environment

python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

1. Install dependencies

pip install -r requirements.txt

1. Configure environment variables

cp .env.example .env
# Edit .env with your settings (database, API keys, etc.)

1. Set up the database

# Create a PostgreSQL database
# Then run migrations (once implemented)

1. Run the server

uvicorn app.main:app --reload

1. Access the API documentation

• Swagger UI: http://localhost:8000/api/docs
• ReDoc: http://localhost:8000/api/redoc

📋 Project Structure

langgraph-multiagent-boilerplate/
├── app/
│   ├── api/
│   │   ├── exceptions.py       # Error handling
│   │   ├── middleware/         # Security & auth middleware
│   │   └── routes/             # API endpoints
│   ├── core/
│   │   ├── config.py           # Configuration management
│   │   └── langgraph/          # LangGraph components
│   ├── db/
│   │   └── base.py             # Database setup
│   ├── models/                 # SQLAlchemy models
│   ├── schemas/                # Pydantic schemas
│   ├── services/               # Business logic
│   └── main.py                 # Application entry point
├── tests/                      # Test suite
├── .env.example                # Environment template
├── pyproject.toml             # Python project metadata
├── requirements.txt           # Dependencies
├── README.md                  # This file
├── PROJECT_OVERVIEW.md        # Detailed project documentation
└── IMPLEMENTATION_TASKS.md    # Development roadmap

🧠 How It Works

Multi-Agent System Architecture

1. AI Crews: Each AI agent cluster contains multiple crews, each led by a supervisor agent
2. Supervisor Architecture: The supervisor agent analyzes user input, creates plans, and assigns tasks to other agents
3. Tool Integration: Agents can access external tools via MCP servers
4. Streaming Communication: Real-time responses with event streaming
5. Persistence: All conversations, states, and activities are stored in the database

Example Flow

1. User sends a message to a crew
2. Supervisor agent receives the input via API call
3. Supervisor analyzes the input and the crew's capabilities
4. Supervisor either answers directly or creates a detailed plan
5. If needed, supervisor assigns tasks to specialized agents
6. Agents perform their tasks using attached MCP tools
7. Supervisor collects results, analyzes them, and formulates a response
8. Response is streamed back to the user

🔌 API Reference

Core Endpoints

Crews and Agents

• GET /api/crews - List all crews
• POST /api/crews - Create a new crew
• GET /api/crews/{crew_id} - Get crew details
• PUT /api/crews/{crew_id} - Update a crew
• DELETE /api/crews/{crew_id} - Delete a crew

• GET /api/agents - List all agents
• POST /api/agents - Create a new agent
• GET /api/agents/{agent_id} - Get agent details
• PUT /api/agents/{agent_id} - Update an agent
• DELETE /api/agents/{agent_id} - Delete an agent

Conversations

• GET /api/conversations - List conversations
• POST /api/conversations - Create a new conversation
• GET /api/conversations/{conversation_id} - Get conversation details
• POST /api/conversations/{conversation_id}/chat - Send a message and get a response
• POST /api/conversations/{conversation_id}/chat/stream - Get streaming response

See the Swagger documentation for the complete API reference.

📝 Usage Examples

Creating a Crew with Agents

import httpx

# Create a new crew
crew_data = {
    "name": "Research Crew",
    "description": "A crew specialized in research tasks",
    "metadata": {"specialization": "research"}
}

response = httpx.post("http://localhost:8000/api/crews", json=crew_data)
crew = response.json()
crew_id = crew["id"]

# Create a supervisor agent
supervisor_data = {
    "crew_id": crew_id,
    "name": "Research Supervisor",
    "description": "Supervises research operations",
    "system_prompt": "You are a research supervisor responsible for coordinating research efforts.",
    "model": "google/gemini-2.5-flash",
    "is_supervisor": True,
    "metadata": {}
}

httpx.post("http://localhost:8000/api/agents", json=supervisor_data)

# Create specialized agents
web_researcher_data = {
    "crew_id": crew_id,
    "name": "Web Researcher",
    "description": "Specializes in web research",
    "system_prompt": "You are a web researcher that finds accurate information online.",
    "model": "claude-3-sonnet",
    "is_supervisor": False,
    "metadata": {"specialty": "web_search"}
}

httpx.post("http://localhost:8000/api/agents", json=web_researcher_data)

Starting a Conversation

# Create a conversation with a crew
conversation_data = {
    "user_id": "user123",
    "crew_id": crew_id,
    "title": "Research on AI trends"
}

response = httpx.post("http://localhost:8000/api/conversations", json=conversation_data)
conversation = response.json()
conversation_id = conversation["id"]

# Send a message to the crew
message_data = {
    "message": "What are the latest trends in multi-agent AI systems?",
    "metadata": {}
}

# For non-streaming response
response = httpx.post(
    f"http://localhost:8000/api/conversations/{conversation_id}/chat", 
    json=message_data
)
print(response.json()["content"])

# For streaming response
with httpx.stream(
    "POST",
    f"http://localhost:8000/api/conversations/{conversation_id}/chat/stream",
    json=message_data,
    timeout=60.0
) as response:
    for chunk in response.iter_lines():
        if chunk.startswith("data: "):
            data = json.loads(chunk[6:])
            if "choices" in data and data["choices"][0]["delta"].get("content"):
                print(data["choices"][0]["delta"]["content"], end="")

🧪 Testing

Run the test suite with:

pytest

🔧 Configuration

Key environment variables:

• DATABASE_URL: PostgreSQL connection string
• OPENROUTER_API_KEY: OpenRouter API key
• MCP_SERVER_URL: URL of the MCP server
• R2_ENDPOINT, R2_BUCKET_NAME, etc.: Cloudflare R2 configuration
• JWT_SECRET_KEY: Secret for JWT authentication
• DEBUG: Enable debug mode

See .env.example for a complete list of configuration options.

🧩 Extending the Boilerplate

Adding New MCP Tools

1. Register a new MCP server in the database
2. Discover and register tools from the server
3. Assign tools to agents

Creating Custom Agent Types

1. Create a new agent with specialized system prompt
2. Assign relevant MCP tools to the agent
3. Add the agent to a crew

Implementing Custom Workflows

1. Modify the supervisor logic in app/core/langgraph/supervisor.py
2. Adjust the state graph to implement your custom workflow

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

📚 Resources

• LangGraph Documentation
• Model Context Protocol
• FastAPI Documentation
• SQLAlchemy Documentation

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: mrgoonie
• Source: mrgoonie/langgraph-multiagent-boilerplate
• License: MIT

Install and usage instructions live in the source repository linked above.