A production-ready Model Context Protocol (MCP) server that provides seamless integration with the LangSmith observability platform. This server enables language models to fetch conversation history and prompts from LangSmith.

The LangSmith MCP Server bridges the gap between language models and the LangSmith platform, enabling advanced capabilities for conversation tracking, prompt management, and analytics integration.

1. Install uv (a fast Python package installer and resolver):

   curl -LsSf https://astral.sh/uv/install.sh | sh

2. Clone this repository and navigate to the project directory:

   git clone https://github.com/langchain-ai/langsmith-mcp-server.git
   cd langsmith-mcp-server

Once you have the LangSmith MCP Server, you can integrate it with various MCP-compatible clients. You have two installation options:

1. Install the package:

   uv run pip install --upgrade langsmith-mcp-server

2. Add to your client MCP config:

   {
       "mcpServers": {
           "LangSmith API MCP Server": {
               "command": "/path/to/uvx",
               "args": [
                   "langsmith-mcp-server"
               ],
               "env": {
                   "LANGSMITH_API_KEY": "your_langsmith_api_key"
               }
           }
       }
   }

Add the following configuration to your MCP client settings:

{
    "mcpServers": {
        "LangSmith API MCP Server": {
            "command": "/path/to/uvx",
            "args": [
                "--directory",
                "/path/to/langsmith-mcp-server/langsmith_mcp_server",
                "run",
                "server.py"
            ],
            "env": {
                "LANGSMITH_API_KEY": "your_langsmith_api_key"
            }
        }
    }
}

Replace the following placeholders:

• /path/to/uv: The absolute path to your uv installation (e.g., /Users/username/.local/bin/uv). You can find it running which uv.
• /path/to/langsmith-mcp-server: The absolute path to your langsmith-mcp project directory
• your_langsmith_api_key: Your LangSmith API key

Example configuration:

{
    "mcpServers": {
        "LangSmith API MCP Server": {
            "command": "/Users/mperini/.local/bin/uvx",
            "args": [
                "langsmith-mcp-server"
            ],
            "env": {
                "LANGSMITH_API_KEY": "lsv2_pt_1234"
            }
        }
    }
}

Copy this configuration in Cursor > MCP Settings.

If you want to develop or contribute to the LangSmith MCP Server, follow these steps:

1. Create a virtual environment and install dependencies:

   uv sync

2. To include test dependencies:

   uv sync --group test

3. View available MCP commands:

   uvx langsmith-mcp-server

4. For development, run the MCP inspector:

   uv run mcp dev langsmith_mcp_server/server.py

   • This will start the MCP inspector on a network port
   • Install any required libraries when prompted
   • The MCP inspector will be available in your browser
   • Set the LANGSMITH_API_KEY environment variable in the inspector
   • Connect to the server
   • Navigate to the "Tools" tab to see all available tools

5. Before submitting your changes, run the linting and formatting checks:

   make lint
   make format

The server enables powerful capabilities including:

• 💬 Conversation History: "Fetch the history of my conversation with the AI assistant from thread 'thread-123' in project 'my-chatbot'"
• 📚 Prompt Management: "Get all public prompts in my workspace"
• 🔍 Smart Search: "Find private prompts containing the word 'joke'"
• 📝 Template Access: "Pull the template for the 'legal-case-summarizer' prompt"
• 🔧 Configuration: "Get the system message from a specific prompt template"

This project is distributed under the MIT License. For detailed terms and conditions, please refer to the LICENSE file.

Made with ❤️ by the LangChain Team