New teammates read the README. AI agents read instruction files.
Direct answer
An agent instruction file, such as AGENTS.md or a tool-specific equivalent, lives in your repository and tells AI coding agents how to work on your project. Include setup, build and test commands, conventions and rules, keep it concise and update it when practices change.
What to include
- Commands: install, run, test, lint.
- Structure: where code and tests live.
- Conventions: naming, formatting, patterns to follow.
- Do not: files not to edit, risky operations.
- Definition of done: tests pass, lint clean.
Example
# Project notes
## Commands
- Install: `npm install`
- Test: `npm test`
- Lint: `npm run lint`
## Conventions
- TypeScript strict mode.
- Components live in `src/components`.
## Rules
- Never edit `generated/`.
- Add a test for every bug fix.
Tips
- Be specific and short.
- Review it like code.
- Keep secrets out of it.
Where Teyro fits
Teyro's Working with AI Coding Agents course turns this into short lessons you can play in a few minutes a day. It has 60 lessons, and you can start free.
The bottom line
A small file that saves a lot of repeated instructions.
