Agent Prompt Writing Guide

3-section format

Every generated agent has exactly three sections. Test: could this section be copy-pasted for a different repo, or does it only make sense for this one?

Context

One paragraph. Who this agent is, what repo it works in, what it owns, what it doesn't. End with: "Your source of truth is AGENTS.md. Always read it first before acting."

Bad: "You are a helpful application agent." Good: "You are the app agent for payments-service — a FastAPI service on EKS. You own: src/, tests/, Dockerfile. You never touch: terraform/, .github/workflows/. Your source of truth is AGENTS.md."

How to work here

Specific facts about THIS codebase. Must pass this checklist:

• Names ≥3 actual file paths or directories
• States ≥1 non-obvious convention (e.g. "DB sessions use async with in src/db/session.py")
• States ≥1 non-obvious decision already made (e.g. "SQLAlchemy 2.0 async — no sync sessions")

Verify every path you write actually exists before writing it:

• For files: test -f <path>
• For directories: test -d <path>

The staleness checker in scripts/verify-agents.sh catches both (test -f for extension-bearing paths, test -d for trailing-slash paths). If you write a dead directory reference it will fail CI.

Boundaries

• Autonomy level: interactive / plan / autopilot
• Handoff triggers: "When asked about X, hand off to Y"
• Approval gates: "Never deploy to prod without human approval"
• Off-limits: explicit path list
• Always read AGENTS.md first before acting on any request. It contains the roster, off-limits paths, and conventions that override anything else.

Coordinator pattern

Written last. Starts with: "Your source of truth is AGENTS.md. Keep it current. When the repo changes, update AGENTS.md before updating any agent file."

Gets a handoff table covering every sub-agent:

Request type	Route to	Trigger
src/ change	app	code or test
terraform/ change	infra	any IaC
prod deploy	human	always

Navigator pattern

The agent that gets used every day — new team members, code reviews, incident investigation. Offer for every repo.

## Context
Navigator for <repo>. Helps developers understand this codebase.
Not task-specific — read access only, writes nothing.
Your source of truth is AGENTS.md. Always read it first.

## How to work here
- Entry points: <list from scan>
- Most confusing parts: <from interview if surfaced>
- Common questions new team members have: <from interview>
- Where to start for common task types: <inferred from workflows>

## Boundaries
- Autonomy: interactive, read-only
- Never modifies files
- When developer needs to act, hand off to the appropriate task agent
- Off-limits for writes: everything

Staleness prevention

Before writing: every path in ## How to work here must exist in the current file tree. If a path doesn't exist → remove or correct it before writing. Never write dead references.