Postgres MCP

A lightweight MCP (Model Context Protocol) server built to query Postgres database using SQL or plain English commands. It provides comprehensive tools for database operations, table introspection, and query execution with smart permission handling.

Features

Smart Query Permission Handling

• Read-only queries: Automatically approved (SELECT, EXPLAIN, SHOW, VALUES)
• Read-write queries: User confirmation required (INSERT, UPDATE, DELETE, MERGE)
• Admin/DDL queries: Elevated permission required (CREATE, ALTER, DROP, etc.)
• Dry-run mode: Validate queries without execution

Comprehensive Table Introspection

• Column definitions with types and constraints
• Primary and foreign key relationships
• Index definitions
• Triggers and check constraints

Database Management

• Multiple database switching capability
• Robust error handling and rollback

Available Tools

| Tool | Description | | ----------------------- | -------------------------------------------------------- | | execute_raw_query | Execute SQL queries with permission validation and dry-run support | | list_tables | List all non-system tables | | describe_tables | Get comprehensive table information including columns, indexes, triggers, and constraints | | switch_database | Switch the active database connection |

Minimum needed environment variables

1. POSTGRES_HOST
2. POSTGRES_USER
3. POSTGRES_PASSWORD
4. POSTGRES_DATABASE

Other environment variables

1. POSTGRES_PORT
2. POSTGRES_SSL (boolean)
3. POSTGRES_VERIFY (boolean)
4. POSTGRES_SEND_RECEIVE_TIMEOUT (in seconds)
5. POSTGRES_CONNECT_TIMEOUT (in seconds)

Configuring using mcpServers json

For Mac and Linux

{
  "mcpServers": {
    "postgres-mcp": {
      "command": "npx",
      "args": ["-y", "@freakynit/postgres-mcp@latest"],
      "env": {
        "POSTGRES_HOST": "<POSTGRES HOST>",
        "POSTGRES_USER": "<POSTGRES USER>",
        "POSTGRES_PASSWORD": "<POSTGRES PASSWORD>",
        "POSTGRES_DATABASE": "<POSTGRES DATABASE>"
      }
    }
  }
}

For Windows

{
  "mcpServers": {
    "postgres-mcp": {
      "command": "cmd",
      "args": ["/k", "npx", "-y", "@freakynit/postgres-mcp@latest"],
      "env": {
        "POSTGRES_HOST": "<POSTGRES HOST>",
        "POSTGRES_USER": "<POSTGRES USER>",
        "POSTGRES_PASSWORD": "<POSTGRES PASSWORD>",
        "POSTGRES_DATABASE": "<POSTGRES DATABASE>"
      }
    }
  }
}

Development Docs

Prerequisites

• Node.js
• A PostgreSQL server

Installation

npm i -g @freakynit/postgres-mcp

OR

git clone https://github.com/freakynit/postgres-mcp.git
cd postgres-mcp
npm install

Configuration

Create a .env file in the project root with the following variables:

# PostgreSQL
POSTGRES_HOST=your-db-host
POSTGRES_PORT=5432                      # Optional, default 5432
POSTGRES_USER=your-username
POSTGRES_PASSWORD=your-password
POSTGRES_DATABASE=your-database

# SSL settings (optional)
POSTGRES_SSL=false                      # Or true
POSTGRES_VERIFY=false                   # Verify server cert if SSL true

# Timeouts (optional, seconds)
POSTGRES_SEND_RECEIVE_TIMEOUT=60        # Query timeout
POSTGRES_CONNECT_TIMEOUT=60             # Connection timeout

Usage

Local Development

Start the server (Starts in stdio mode):

node src/index.js

With MCP Inspector

For debugging and development:

npx @modelcontextprotocol/inspector node src/index.js

Debugging with MCP inspector

npx @modelcontextprotocol/inspector node src/index.js

License

This project is licensed under the MIT License. See LICENSE for details.