PostgreSQL MCP Server

A Model Context Protocol (MCP) server that provides tools for connecting to and querying PostgreSQL databases.

Features

• Connect to PostgreSQL: Connect to any PostgreSQL database with credentials
• Schema Discovery: List all schemas in the database
• Table Discovery: List all tables in a schema
• Table Description: Get detailed information about table structure, including columns, types, constraints, and relationships
• Query Execution: Run SELECT queries safely with parameter support

Installation

npm install
npm run build

Usage

As an MCP Server

Add to your MCP client configuration (e.g., Claude Desktop, Cline):

Option 1: Auto-connect with Environment Variables (Recommended)

{
  "mcpServers": {
    "postgres": {
      "command": "node",
      "args": ["/path/to/postgres-mcp-server/build/index.js"],
      "env": {
        "PG_HOST": "your-host",
        "PG_PORT": "5432",
        "PG_USER": "your-user",
        "PG_PASSWORD": "your-password",
        "PG_DATABASE": "your-database"
      }
    }
  }
}

When environment variables are configured, the server will automatically connect on startup.

Option 2: Manual Connection

{
  "mcpServers": {
    "postgres": {
      "command": "node",
      "args": ["/path/to/postgres-mcp-server/build/index.js"]
    }
  }
}

Without environment variables, use the connect_db tool to connect manually.

Quick Setup for Cursor

The file cursor-mcp-config.json contains a ready-to-use configuration. Add this to your ~/.cursor/mcp.json file under the mcpServers section.

Available Tools

1. connect_db

Connect to a PostgreSQL database.

Parameters:

• host (required): Database host
• port (optional): Database port (default: 5432)
• database (required): Database name
• user (required): Database user
• password (required): Database password

Example:

{
  "host": "localhost",
  "port": 5432,
  "database": "mydb",
  "user": "postgres",
  "password": "mypassword"
}

2. list_schemas

List all schemas in the connected database (excludes system schemas).

Parameters: None

3. list_tables

List all tables in a specific schema.

Parameters:

• schema (optional): Schema name (default: "public")

4. describe_table

Get detailed information about a table's structure.

Parameters:

• schema (optional): Schema name (default: "public")
• table (required): Table name

Returns column names, data types, nullability, defaults, primary keys, and foreign key relationships.

5. query

Execute a SELECT query on the database.

Parameters:

• sql (required): SQL SELECT query (use $1, $2, etc. for parameters)
• params (optional): Array of query parameters

Example:

{
  "sql": "SELECT * FROM users WHERE age > $1 AND city = $2",
  "params": [18, "New York"]
}

Note: Only SELECT queries are allowed for safety. The tool validates that queries start with SELECT.

Development

Build

npm run build

Project Structure

postgres-mcp-server/
├── src/
│   └── index.ts          # Main server implementation
├── build/                # Compiled JavaScript output
├── package.json
├── tsconfig.json
└── README.md

Security Considerations

• This server only allows SELECT queries through the query tool to prevent accidental data modification
• Database credentials are required for each connection
• Use environment variables or secure credential management for production deployments
• Always use parameterized queries to prevent SQL injection

Requirements

• Node.js 18 or higher
• PostgreSQL database (any version supported by the pg library)

License

MIT