langchain-mcp

Give Claude superpowers for LangChain development

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Features

Knowledge Search

Search LangChain, LangGraph, LangSmith & DeepAgents documentation and source code instantly from Claude.

LangGraph Agent Debugging (New in v2!)

Debug your LangGraph agents like Polly - connect to your local langgraph dev server and:

• List threads, runs, and traces
• Inspect agent state and checkpoints
• Ask "Why did this fail?" and get AI-powered analysis
• Get suggestions to improve your agent's prompts

Install

npm i -g langchain-mcp
langchain-mcp login
claude mcp add langchain-mcp -- langchain-mcp

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "langchain-mcp": {
      "command": "langchain-mcp"
    }
  }
}

Tools

Search (requires login)

| Tool | Description | |------|-------------| | search_docs | Search documentation and tutorials | | search_langchain_code | Search LangChain source code | | search_langgraph_code | Search LangGraph source code | | search_deepagents_code | Search DeepAgents source code |

Debug LangGraph Agents (free, no login)

| Tool | Description | |------|-------------| | langgraph_list_threads | List threads from local server | | langgraph_get_thread | Get thread details | | langgraph_get_thread_state | Get state/checkpoint | | langgraph_list_runs | List runs for a thread | | langgraph_get_run | Get run trace details |

Debug Your Agents

# Start your LangGraph server
langgraph dev

Then ask Claude:

• "List my LangGraph threads"
• "What went wrong with thread abc123?"
• "Summarize the last run"
• "How can I improve this agent?"

Connects to localhost:2024 by default.

Pricing

| Feature | Cost | |---------|------| | Doc/Code Search | $5 free credits (~2000 searches) | | LangGraph Debugging | Free forever |

License

MIT