Postgres

It enforces read-only mode at the connection level and validates queries to block any writes, so you can point it at production without sweating. The multi-database config is smart: you describe what each database contains and Claude picks the right one based on context. Comes with schema exploration, configurable SSL, and sensible limits like 10k rows max and 30 second timeouts. The setup is straightforward if you're comfortable dropping credentials in a JSON file, though you'll want to chmod 600 it. Good for ad-hoc analysis, debugging data issues, or letting Claude explore your schema to write better queries.