PostgreSQL MCP Server

PostgreSQL MCP Server

A Model Context Protocol (MCP) server that provides access to PostgreSQL database schemas and metadata. This server allows Cursor and other MCP-compatible tools to explore your database structure, inspect table schemas, and understand relationships.

Features

• List Tables: Get all tables in a schema with basic information
• Describe Table: Get detailed column information for any table
• Table Relationships: Explore foreign key relationships
• List Schemas: See all available schemas in your database
• Index Information: View indexes for specific tables

Prerequisites

• Node.js 18+
• PostgreSQL database (local or remote)
• npm or yarn package manager

Installation

1. Clone or download this repository
2. Install dependencies:
   npm install
3. Configure database connection:
   cp config.env.example .env
   Edit the .env file with your PostgreSQL connection details:
   DB_HOST=localhost DB_PORT=5432 DB_NAME=your_database_name DB_USER=your_username DB_PASSWORD=your_password
4. Test the server (optional):
   npm start

Cursor Integration

To use this MCP server with Cursor, you need to add it to your Cursor configuration.

Step 1: Add to Cursor MCP Configuration

Open Cursor and go to Settings → Features → Model Context Protocol, or edit your MCP configuration file directly.

Add the following configuration:

Important: Replace /absolute/path/to/pg_mcp/src/index.js with the actual absolute path to your src/index.js file.

Step 2: Alternative Configuration (Using .env file)

If you prefer to use the .env file for configuration:

Step 3: Restart Cursor

After adding the configuration, restart Cursor to load the MCP server.

Available Tools

Once configured, you'll have access to these tools in Cursor:

list_tables

Lists all tables in a specified schema (defaults to 'public')

describe_table

Gets detailed schema information for a specific table

get_table_relationships

Shows foreign key relationships for a table

list_schemas

Lists all available schemas in the database

get_indexes

Shows indexes for a specific table

Usage Examples

Once configured in Cursor, you can ask questions like:

• "What tables are in my database?"
• "Show me the schema for the users table"
• "What are the foreign key relationships for the orders table?"
• "List all indexes on the products table"
• "What schemas are available in my database?"

Troubleshooting

Connection Issues

1. Database connection fails:
   • Verify your database credentials in .env
   • Ensure PostgreSQL is running
   • Check if the database allows connections from your host
2. MCP server not loading in Cursor:
   • Verify the absolute path to index.js is correct
   • Check that Node.js is installed and accessible
   • Review Cursor's MCP logs for error messages
3. Permission denied errors:
   • Ensure the database user has read permissions on information_schema
   • Grant necessary SELECT permissions on system tables

Common Error Messages

• Database connection failed: Check your connection parameters
• Table not found: Verify the table name and schema
• Permission denied: Ensure your database user has appropriate read permissions

Security Considerations

• This server only reads database metadata (schema information)
• No actual table data is accessed or exposed
• Uses parameterized queries to prevent SQL injection
• Database credentials are stored locally in your environment

Development

To run in development mode with auto-reload:

License

MIT License - see LICENSE file for details.