Your Agent's Instruction Manual
CLAUDE.md, AGENTS.md, local overrides, rules folders, and why every coding agent has a slightly different filing cabinet.
Coding agents need instructions. The annoying part is that every tool has its own convention.
You will see files like AGENTS.md, CLAUDE.md, project-level config folders, local override files, and rules directories. They all do roughly the same job: tell the agent how this project works and what behavior to prefer.
The scopes
Global instructions apply across your machine or account.
Project instructions live in the repo and should describe architecture, commands, testing, deploy rules, and dangerous gotchas.
Folder instructions may apply only under a subdirectory.
Local overrides are personal instructions that should not be committed, like machine-specific paths or preferences.
What belongs there
Good instruction files contain commands, architecture, coding style, test expectations, deployment warnings, and rules about secrets or generated files.
Bad instruction files contain vague personality wishes and stale architecture fan fiction.
The practical habit
When an agent repeats a mistake, write the correction where the agent will actually read it next time. The instruction file is not documentation for humans only. It is part of your tooling.