LangChain Agent MCP Server

A production-ready MCP server exposing LangChain agent capabilities through the Model Context Protocol, deployed on Google Cloud Run.

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🚀 Overview

This is a standalone backend service that wraps a LangChain agent as a single, high-level MCP Tool. The server is built with FastAPI and deployed on Google Cloud Run, providing a scalable, production-ready solution for exposing AI agent capabilities to any MCP-compliant client.

Live Service: https://langchain-agent-mcp-server-554655392699.us-central1.run.app

✨ Features

✅ MCP Compliance - Full Model Context Protocol support
✅ LangChain Agent - Multi-step reasoning with ReAct pattern
✅ Google Cloud Run - Scalable, serverless deployment
✅ Tool Support - Extensible framework for custom tools
✅ Production Ready - Error handling, logging, and monitoring
✅ Docker Support - Containerized for easy deployment

🏗️ Architecture

Component	Technology	Purpose
Backend Framework	FastAPI	High-performance, asynchronous web server
Agent Framework	LangChain	Multi-step reasoning and tool execution
Deployment	Google Cloud Run	Serverless, auto-scaling hosting
Containerization	Docker	Consistent deployment environment
Protocol	Model Context Protocol (MCP)	Standardized tool and context sharing

🛠️ Quick Start

Prerequisites

Python 3.11+
OpenAI API key
Google Cloud account (for Cloud Run deployment)
Docker (optional, for local testing)

Local Development

Clone the repository:
git clone https://github.com/mcpmessenger/LangchainMCP.git cd LangchainMCP
Install dependencies:
# Windows py -m pip install -r requirements.txt # Linux/Mac pip install -r requirements.txt
Set up environment variables: Create a .env file:
OPENAI_API_KEY=your-openai-api-key-here OPENAI_MODEL=gpt-4o-mini PORT=8000
Run the server:
# Windows py run_server.py # Linux/Mac python run_server.py
Test the endpoints:
- Health: http://localhost:8000/health
- Manifest: http://localhost:8000/mcp/manifest
- API Docs: http://localhost:8000/docs

☁️ Google Cloud Run Deployment

The server is designed for deployment on Google Cloud Run. See our comprehensive deployment guides:

DEPLOY_CLOUD_RUN_WINDOWS.md - Windows deployment guide
DEPLOY_CLOUD_RUN.md - General deployment guide
QUICK_DEPLOY.md - Quick reference

Quick Deploy

# Windows PowerShell .\deploy-cloud-run.ps1 -ProjectId "your-project-id" -Region "us-central1" # Linux/Mac ./deploy-cloud-run.sh your-project-id us-central1

Current Deployment

Service URL: https://langchain-agent-mcp-server-554655392699.us-central1.run.app
Project: slashmcp
Region: us-central1
Status: ✅ Live and operational

📡 API Endpoints

MCP Endpoints

Get Manifest

GET /mcp/manifest

Returns the MCP manifest declaring available tools.

Response:

{ "name": "langchain-agent-mcp-server", "version": "1.0.0", "tools": [ { "name": "agent_executor", "description": "Execute a complex, multi-step reasoning task...", "inputSchema": { "type": "object", "properties": { "query": { "type": "string", "description": "The user's query or task" } }, "required": ["query"] } } ] }

Invoke Tool

POST /mcp/invoke Content-Type: application/json { "tool": "agent_executor", "arguments": { "query": "What is the capital of France?" } }

Response:

{ "content": [ { "type": "text", "text": "The capital of France is Paris." } ], "isError": false }

Other Endpoints

GET / - Server information
GET /health - Health check
GET /docs - Interactive API documentation (Swagger UI)

🔧 Configuration

Environment Variables

Variable	Description	Default	Required
`OPENAI_API_KEY`	OpenAI API key	-	✅ Yes
`OPENAI_MODEL`	OpenAI model to use	`gpt-4o-mini`	No
`PORT`	Server port	`8000`	No
`API_KEY`	Optional API key for authentication	-	No
`MAX_ITERATIONS`	Maximum agent iterations	`10`	No
`VERBOSE`	Enable verbose logging	`false`	No

📚 Documentation

📖 Full Documentation Site - Complete documentation with examples (GitHub Pages)

Quick Links:

Getting Started - Set up and run locally
Examples - Code examples including "Build a RAG agent in 10 lines"
Deployment Guide - Deploy to Google Cloud Run
API Reference - Complete API documentation
Troubleshooting - Common issues and solutions

Build Docs Locally:

# Windows .\build-docs.ps1 serve # Linux/Mac ./build-docs.sh serve

Additional Guides:

README_BACKEND.md - Complete technical documentation
DEPLOY_CLOUD_RUN_WINDOWS.md - Windows deployment guide
INSTALL_PREREQUISITES.md - Prerequisites installation
SLASHMCP_INTEGRATION.md - SlashMCP integration guide

🧪 Testing

# Test health endpoint Invoke-WebRequest -Uri "https://langchain-agent-mcp-server-554655392699.us-central1.run.app/health" # Test agent invocation $body = @{ tool = "agent_executor" arguments = @{ query = "What is 2+2?" } } | ConvertTo-Json Invoke-WebRequest -Uri "https://langchain-agent-mcp-server-554655392699.us-central1.run.app/mcp/invoke" ` -Method POST ` -ContentType "application/json" ` -Body $body

🏗️ Project Structure

. ├── src/ │ ├── main.py # FastAPI application with MCP endpoints │ ├── agent.py # LangChain agent definition and tools │ ├── mcp_manifest.json # MCP manifest configuration │ └── start.sh # Cloud Run startup script ├── tests/ │ └── test_mcp_endpoints.py # Test suite ├── Dockerfile # Container configuration ├── requirements.txt # Python dependencies ├── deploy-cloud-run.ps1 # Windows deployment script ├── deploy-cloud-run.sh # Linux/Mac deployment script └── cloudbuild.yaml # Cloud Build configuration

🚀 Deployment Options

Google Cloud Run (Recommended)

Scalable - Auto-scales based on traffic
Serverless - Pay only for what you use
Managed - No infrastructure to manage
Fast - Low latency with global CDN

See DEPLOY_CLOUD_RUN_WINDOWS.md for detailed instructions.

Docker (Local/Other Platforms)

docker build -t langchain-agent-mcp-server . docker run -p 8000:8000 -e OPENAI_API_KEY=your-key langchain-agent-mcp-server

📊 Performance

P95 Latency: < 5 seconds for standard 3-step ReAct chains
Scalability: Horizontal scaling on Cloud Run
Uptime: 99.9% target (Cloud Run SLA)
Throughput: Handles concurrent requests efficiently

🔒 Security

API key authentication (optional)
Environment variable management
Secret Manager integration (Cloud Run)
HTTPS by default (Cloud Run)
CORS configuration

🤝 Contributing

We welcome contributions! Please see our contributing guidelines.

Fork the repository
Create a feature branch
Make your changes
Submit a pull request

📜 License

This project is licensed under the MIT License.

🔗 Links

GitHub Repository: https://github.com/mcpmessenger/LangchainMCP
Live Service: https://langchain-agent-mcp-server-554655392699.us-central1.run.app
API Documentation: https://langchain-agent-mcp-server-554655392699.us-central1.run.app/docs
Model Context Protocol: https://modelcontextprotocol.io/

🙏 Acknowledgments

Built with LangChain
Deployed on Google Cloud Run
Uses FastAPI for the web framework

Status: ✅ Production-ready and deployed on Google Cloud Run

LangChain Agent MCP Server

LangChain Agent MCP Server

🚀 Overview

✨ Features

🏗️ Architecture

🛠️ Quick Start

Prerequisites

Local Development

☁️ Google Cloud Run Deployment

Quick Deploy

Current Deployment

📡 API Endpoints

MCP Endpoints

Get Manifest

Invoke Tool

Other Endpoints

🔧 Configuration

Environment Variables

📚 Documentation

🧪 Testing

🏗️ Project Structure

🚀 Deployment Options

Google Cloud Run (Recommended)

Docker (Local/Other Platforms)

📊 Performance

🔒 Security

🤝 Contributing

📜 License

🔗 Links

🙏 Acknowledgments

Related Resources

New MCP Servers

MCP directory API