MCP-LangGraph Agents: A Multi-Agent Orchestration Framework Based on Model Context Protocol

This project demonstrates how to combine the Model Context Protocol (MCP) with LangGraph to build a modular AI workflow system that supports state persistence and multi-agent collaboration. The core goal is to solve the problem of seamless collaboration between different agents, tools, and data sources, and achieve a balance between interoperability and scalability through the combination of standardized protocols and flexible orchestration frameworks.

With the popularization of AI agent applications, inconsistent interface specifications across different frameworks lead to high integration costs and fragmented ecosystems. The MCP proposed by Anthropic is an open standard to address this issue, defining a unified protocol for AI models to securely access external tools; as an extension of LangChain, LangGraph provides state machine and graph structure orchestration capabilities, making it suitable for complex multi-agent workflows. This project combines the two to create a standardized yet flexible system.

Core Components

1. MCP Server Layer: Implemented using FastMCP as an stdio server, exposing a unified agent_chat interface
2. LangGraph Graph Orchestration Layer: A workflow graph built with StateGraph, including four agent nodes: routing, to-do, analysis, and echo
3. State Management Layer: MemorySaver implements session state persistence, retaining conversation history and to-do lists

Workflow

Client call → Input validation → Graph execution (routing node scheduling) → Agent processing → Response assembly → Result return

Code Structure

src/mcp_langgraph_agents/ contains graph.py (graph definition, state, routing), server.py (MCP server); main.py is the entry point, and pyproject.toml manages dependencies.

Tool Contract Example

Input: {"message":"Summarize why testing is needed and add a to-do: stabilize CI","thread_id":"demo-thread"} Output: JSON containing a list of agent responses and the current to-do list

Quick Start

• Environment: Python3.11+
• Installation: pip install -e .
• Launch: mcp-langgraph-server or python main.py
• Call: Connect to the server via MCP client and call the agent_chat tool

Design Highlights

Balance between standardization and flexibility, concise state persistence, deterministic agent design, modular expansion (adding new agents without modifying the server layer)

This architecture applies to:

1. Enterprise internal tool integration: Encapsulate internal services as MCP tools and expose them via a standardized AI interface
2. Multi-agent collaboration systems: Different specialized agents collaborate to complete tasks such as code review and document generation
3. Conversational applications: Chatbots and customer service systems that maintain long-term context
4. Workflow automation: Model business processes as graph structures, with AI agents executing them automatically

The MCP-LangGraph Agents project provides a clear reference implementation for modular, scalable multi-agent systems, demonstrating the feasibility of the MCP protocol and the orchestration capabilities of LangGraph. For developers exploring AI agent architectures, it is a worthy example to learn from. The standardization of the MCP ecosystem enables tools to be developed once and used in multiple scenarios, promoting seamless collaboration between tools from different frameworks.