No config step, the tools discover everything from pg_catalog at call time. list_schemas → list_tables → describe_table is the typical agent workflow, and there's a query_guide prompt baked in that suggests that progression.

On query guardrails: every query runs in a readonly transaction and results are capped at 500 rows via a wrapping SELECT * FROM (...) sub LIMIT 500. There's also explain_query which returns the plan without executing, so agents can check before running something expensive. That said, there's no cost-based gate that blocks a bad plan automatically; that's an interesting idea worth exploring.