This Claude skill enables secure, read-only access to multiple PostgreSQL databases, allowing users to explore schemas, perform data analysis, and verify database contents without the risk of accidental data modification. It features robust safety guardrails, including read-only session enforcement and query validation, making it an essential tool for developers and data analysts seeking safe database interaction.

When should I use postgres?

postgres is useful in the following scenarios: • Data Analysis & Reporting: Execute complex SELECT queries to extract insights and generate real-time reports from production or staging databases. • Database Schema Exploration: Quickly browse table structures, view column types, and understand database relationships to assist in software development or debugging. • Data Verification: Check specific records, such as user account statuses or transaction history, to troubleshoot issues reported by customers or system logs. • Safe AI Data Retrieval: Provide AI agents with real-time data access while maintaining strict security through read-only sessions, query timeouts, and row limits.

name	postgres
description	"Execute read-only SQL queries against multiple PostgreSQL databases. Use when: (1) querying PostgreSQL databases, (2) exploring database schemas/tables, (3) running SELECT queries for data analysis, (4) checking database contents. Supports multiple database connections with descriptions for intelligent auto-selection. Blocks all write operations (INSERT, UPDATE, DELETE, DROP, etc.) for safety."

PostgreSQL Read-Only Query Skill

Execute safe, read-only queries against configured PostgreSQL databases.

Requirements

Python 3.8+
psycopg2-binary: pip install -r requirements.txt

Setup

Create connections.json in the skill directory or ~/.config/claude/postgres-connections.json.

Security: Set file permissions to 600 since it contains credentials:

chmod 600 connections.json

{
  "databases": [
    {
      "name": "production",
      "description": "Main app database - users, orders, transactions",
      "host": "db.example.com",
      "port": 5432,
      "database": "app_prod",
      "user": "readonly_user",
      "password": "your-password",
      "sslmode": "require"
    }
  ]
}

Config Fields

Field	Required	Description
name	Yes	Identifier for the database (case-insensitive)
description	Yes	What data this database contains (used for auto-selection)
host	Yes	Database hostname
port	No	Port number (default: 5432)
database	Yes	Database name
user	Yes	Username
password	Yes	Password
sslmode	No	SSL mode: disable, allow, prefer (default), require, verify-ca, verify-full

Usage

List configured databases

python3 scripts/query.py --list

Query a database

python3 scripts/query.py --db production --query "SELECT * FROM users LIMIT 10"

List tables

python3 scripts/query.py --db production --tables

Show schema

python3 scripts/query.py --db production --schema

Limit results

python3 scripts/query.py --db production --query "SELECT * FROM orders" --limit 100

Database Selection

Match user intent to database description:

User asks about	Look for description containing
users, accounts	users, accounts, customers
orders, sales	orders, transactions, sales
analytics, metrics	analytics, metrics, reports
logs, events	logs, events, audit

If unclear, run --list and ask user which database.

Safety Features

Read-only session: Connection uses PostgreSQL readonly=True mode (primary protection)
Query validation: Only SELECT, SHOW, EXPLAIN, WITH queries allowed
Single statement: Multiple statements per query rejected
SSL support: Configurable SSL mode for encrypted connections
Query timeout: 30-second statement timeout enforced
Memory protection: Max 10,000 rows per query to prevent OOM
Column width cap: 100 char max per column for readable output
Credential sanitization: Error messages don't leak passwords

Troubleshooting

Error	Solution
Config not found	Create `connections.json` in skill directory
Authentication failed	Check username/password in config
Connection timeout	Verify host/port, check firewall/VPN
SSL error	Try `"sslmode": "disable"` for local databases
Permission warning	Run `chmod 600 connections.json`

Exit Codes

0: Success
1: Error (config missing, auth failed, invalid query, database error)

Workflow

Run --list to show available databases
Match user intent to database description
Run --tables or --schema to explore structure
Execute query with appropriate LIMIT

postgres

When & Why to Use This Skill

Use Cases