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PostgreSQL MCP Agent

This agent uses the PostgreSQL MCP server to interact with PostgreSQL databases. It demonstrates how to:

  • Connect to a PostgreSQL database using MCP (Model Context Protocol)
  • Use uvx to run the MCP server without manual installation
  • Pass database credentials securely via environment variables

Prerequisites

  • PostgreSQL Database: You need access to a PostgreSQL database with a connection string
  • uvx: The agent uses uvx (part of the uv package manager) to run the MCP server

Setup Instructions

1. Configure Database Connection

Create a .env file in the mcp_postgres_agent directory:

POSTGRES_CONNECTION_STRING=postgresql://user:password@host:port/database

Example connection string format:

postgresql://username:password@localhost:5432/mydb
postgresql://postgres.xyz:password@aws-region.pooler.supabase.com:5432/postgres

2. Run the Agent

Start the ADK Web UI from the samples directory:

adk web

The agent will automatically:

  • Load the connection string from the .env file
  • Use uvx to run the postgres-mcp server with unrestricted access mode
  • Connect to your PostgreSQL database

3. Example Queries

Once the agent is running, try these queries:

  • "What tables are in the database?"
  • "Show me the schema for the users table"
  • "Query the first 10 rows from the products table"
  • "What indexes exist on the orders table?"
  • "Create a new table called test_table with columns id and name"

Configuration Details

The agent uses:

  • Model: Gemini 2.0 Flash
  • MCP Server: postgres-mcp (via uvx)
  • Access Mode: Unrestricted (allows read/write operations). Warning: Using unrestricted mode in a production environment can pose significant security risks. It is recommended to use a more restrictive access mode or configure database user permissions appropriately for production use.
  • Connection: StdioConnectionParams with 60-second timeout
  • Environment Variable: DATABASE_URI (mapped from POSTGRES_CONNECTION_STRING)

Troubleshooting

  • Ensure your POSTGRES_CONNECTION_STRING is correctly formatted
  • Verify database credentials and network access
  • Check that uv is installed (pip install uv or brew install uv)