psql · PostgreSQL Global Development Group
PostgreSQL psql for AI Agents
Query PostgreSQL non-interactively with explicit credentials, output, transactions, and write boundaries.
Install for an Agent
Choose an official installation path that matches the runtime. Pin a version for team or CI use, then record the version before the first task.
Structured Output for Reliable Automation
Prefer a machine-readable format. Treat stdout as the result channel and stderr as diagnostics so the agent can parse failures separately.
R0–R3 Command Risk Guide
Risk is assigned per command. R0 is local or remote read-only, R1 is reversible local write, R2 changes remote state, and R3 can be irreversible or production-impacting.
Read-only does not mean public
R0 only means the command does not change local or remote state. A read-only command may still return secrets, identity data, configuration, or production data. Expose only the minimum needed for the task, and never place it in logs, prompts, or commits.
How the Agent Readiness Score Is Built
Readiness describes how reliably an agent can operate the tool. It does not make every command safe and it does not replace an independent execution test.
Documentation indicates an agent-readiness score of 83/100. A bounded local smoke test is recorded for 18.1; review its limitations before relying on untested commands.
Generate a Skill or Agent Policy
Choose an agent and safety mode to generate a copyable artifact with installation, allowed commands, approval boundaries, and the evidence limitation.
---
name: psql-agent-workflow
description: Use PostgreSQL psql for PostgreSQL queries, schema inspection, CSV export with explicit command risk and evidence boundaries.
---
# PostgreSQL psql agent workflow
Use this skill when the task needs PostgreSQL queries, schema inspection, CSV export, migration checks.
## Evidence boundary
- Registry confidence: `verified`
- Documentation checked: `2026-07-10`
- Locally tested version: `18.1`
- Treat only the recorded executed checks as independently verified; every unlisted command remains documentation-only.
## Executed smoke checks
- `psql --version` — passed; exit 0. The recorded smoke check completed successfully.
- `psql --help` — passed; exit 0. The recorded smoke check completed successfully.
## Installation
- Homebrew libpq (macos, linux): `brew install libpq`
## Authentication
- Methods: connection URI, password file, service file, peer authentication
- Secret environment variables: `DATABASE_URL`, `PGHOST`, `PGUSER`, `PGPASSWORD`, `PGSERVICE`
- Minimum permissions: Use a read-only database role, TLS, and a database/schema search path limited to the task.
- Credential storage: For headless runs, inject DATABASE_URL, PGHOST, PGUSER, PGPASSWORD, PGSERVICE from the CI or platform secret manager at process start. For local interactive use, prefer the CLI or operating-system credential store when the official client supports one. Never save values in repository files.
- Never print, persist, or commit credential values.
## Allowed commands (read-only)
- `psql "$DATABASE_URL" --no-psqlrc --csv --command "SELECT * FROM table_name LIMIT 20"` — R0: Executes a bounded SELECT and emits CSV.
## Commands requiring explicit approval (read-only)
- None recorded.
## Forbidden commands (read-only)
- R2 `psql "$DATABASE_URL" --command "BEGIN; UPDATE table_name SET ...; COMMIT;"` — Changes database records and should run in a reviewed transaction.
- R3 `dropdb --if-exists DATABASE_NAME` — Permanently deletes a database.
## Execution rules
1. Mode boundary: R0 exact commands may be used; R1, R2, and R3 commands are forbidden.
2. Confirm the selected account, project, context, database, namespace, or environment before any command.
3. Prefer structured output using `--csv`, `--tuples-only`, `--no-psqlrc`.
4. Capture the exact command, exit code, stdout, and stderr separately.
5. A generated prefix policy must prompt unless that exact prefix is explicitly marked suffix-safe; do not infer safety from the executable name.
6. Never broaden credentials or disable safety controls to make a command succeed.
## Official sources
- [PostgreSQL psql documentation](https://www.postgresql.org/docs/current/app-psql.html)
Verification History and Official Evidence
CLI Finder records documentation review separately from real execution. Installation, help, exit codes, and output cannot be called Verified until they were run.