LangGraph-MCP-Client

# Langgraph-MCP Client for Postgresql Example This repository demonstrates a very low level example of how to interact with an MCP server as a docker image, connected to a PostgreSQL database for LangGraph agents. [model context protocol](https://modelcontextprotocol.io/introduction) >MCP is an open protocol that standardizes how applications provide context to LLMs. Think of MCP like a USB-C port for AI applications. Just as USB-C provides a standardized way to connect your devices to various peripherals and accessories, MCP provides a standardized way to connect AI models to different data sources and tools. --- ## Prerequisites Before you begin, ensure you have the following installed on your system: - [Docker](https://www.docker.com/) - [PostgreSQL Database](https://www.postgresql.org/) - running and populated - [MCP Servers](https://github.com/modelcontextprotocol/servers) --- ## Flow and tools - We use a postgresql database that the Postgresl MCP Server is aware of through the config - `from langchain_mcp_adapters.tools import load_mcp_tools` creates the mcp tool - `create_react_agent` is a fast agent templater - we output the stream to file ## Project Setup Instructions ### 1. Clone the Repository Clone this repository to your local machine: ```bash git clone https://github.com/your-repo/Langchain-MCP.git cd Langgraph-mcp-client directory ``` ### 2. Create a `.env` File Create a `.env` file in the root of the repository with the following variables: ``` DB_HOST=<your-database-host> DB_PORT=<your-database-port> DB_USER=<your-database-username> DB_PASSWORD=<your-database-password> DB_NAME=<your-database-name> ``` Replace the placeholders with your actual database and MCP server connection details. ### 3. Install UV Package Install the UV package globally if you haven't already: [Astral uv](https://docs.astral.sh/uv/) --- ## MCP Server Setup 1. Clone the repo [MCP Servers](https://github.com/modelcontextprotocol/servers) to a separate directory 2. Run - `docker build -t mcp/postgres -f src/postgres/Dockerfile .` to build and tag the image ## Usage Instructions ### 1. Sync the UV Package Run the following command to sync the UV package: ```bash uv sync ``` This command ensures that the UV package installs the package correctly. ### 2. Run the Query Agent #### Start the query agent using the following command: ```bash uv run queryagent ``` This will prompt for the user query #### Alt - with query (Banking database) ```bash uv run queryagent "Who holds the most funds in thier account?" ``` --- ## TODO: - Output formating - Multi agent ## Troubleshooting - **Database Connection**: Verify the `.env` file contains the correct database credentials. - **UV Package Errors**: Ensure the UV CLI is installed globally and the `uv sync` command completes without errors. --- ## Contributing Feel free to open issues or submit pull requests to improve this repository. --- ## License This project is licensed under the MIT License. See the `LICENSE` file for details.