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Langgraph-MCP Client for Postgresql Example

@BrianCusack

Repository

About Langgraph-MCP Client for Postgresql Example

LangGraph implementation interacting with a PostgreSQL MCP Server

Config

Add this server to your MCP-compatible client using the configuration below.

{
  "mcpServers": {
    "LangGraph-MCP-Client": {
      "command": "uv",
      "args": [
        "sync"
      ]
    }
  }
}

Tools

No tools detected

We auto-extract tools from the README. The maintainer can list them under a ## Tools heading to populate this section.

Overview

What is Langgraph-MCP Client for Postgresql Example?

This repository demonstrates a low-level example of how to interact with an MCP server as a Docker image, connected to a PostgreSQL database for LangGraph agents. It is intended for developers who want to integrate PostgreSQL data sources with LangGraph using the Model Context Protocol (MCP).

How to use Langgraph-MCP Client for Postgresql Example?

Clone the repository, create a .env file with database credentials (DB_HOST, DB_PORT, DB_USER, DB_PASSWORD, DB_NAME), install the UV package globally, and build the MCP Postgres Docker image. Then run uv sync followed by uv run queryagent to start the query agent, optionally passing a natural language query as an argument (e.g., uv run queryagent "Who holds the most funds in their account?").

Key features of Langgraph-MCP Client for Postgresql Example

  • Connects to a PostgreSQL database via an MCP server.
  • Uses langchain_mcp_adapters.tools.load_mcp_tools to create MCP tools.
  • Employs LangGraph's create_react_agent for fast agent templating.
  • Outputs the agent’s stream to a file.
  • Accepts user queries via command line.

Use cases of Langgraph-MCP Client for Postgresql Example

  • Querying a banking database using natural language questions.
  • Learning how to integrate a PostgreSQL MCP server with LangGraph agents.
  • Prototyping a LangGraph agent that uses database tools over MCP.

FAQ from Langgraph-MCP Client for Postgresql Example

What are the prerequisites for running this project?

You need Docker, a running PostgreSQL database, and the MCP Servers repository (to build the Postgres MCP image). The UV package manager must also be installed globally.

How do I set up the database connection?

Create a .env file in the repository root with the variables DB_HOST, DB_PORT, DB_USER, DB_PASSWORD, and DB_NAME, replacing placeholders with your actual credentials.

What should I do if I encounter UV package errors?

Ensure the UV CLI is installed globally and that the uv sync command completes without errors.

How do I build the PostgreSQL MCP Server Docker image?

Clone the MCP Servers repository, navigate to its directory, and run docker build -t mcp/postgres -f src/postgres/Dockerfile .

How can I run the query agent with a specific question?

Run uv run queryagent "your question" from the project directory, replacing "your question" with the desired natural language query.

Frequently asked questions

What are the prerequisites for running this project?

You need Docker, a running PostgreSQL database, and the MCP Servers repository (to build the Postgres MCP image). The UV package manager must also be installed globally.

How do I set up the database connection?

Create a `.env` file in the repository root with the variables `DB_HOST`, `DB_PORT`, `DB_USER`, `DB_PASSWORD`, and `DB_NAME`, replacing placeholders with your actual credentials.

What should I do if I encounter UV package errors?

Ensure the UV CLI is installed globally and that the `uv sync` command completes without errors.

How do I build the PostgreSQL MCP Server Docker image?

Clone the MCP Servers repository, navigate to its directory, and run `docker build -t mcp/postgres -f src/postgres/Dockerfile .`

How can I run the query agent with a specific question?

Run `uv run queryagent "your question"` from the project directory, replacing `"your question"` with the desired natural language query.

Comments

Basic information

Category

Reasoning

Transports

stdio

Author

BrianCusack

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