agents-md-facts

agents-md-facts

Honest to a fault — a minimal AGENTS.md, authored from your repo's facts, never guessed.

AI coding agents (Copilot, Cursor, Claude Code, Codex) read one file to learn how to work in your repo: AGENTS.md. There are two ways to get one wrong:

• Write it by hand → it rots. The code moves; the file quietly lies, and your agent obeys the stale version at full confidence.
• Let an LLM write it → it bloats. Peer-reviewed research — Gloaguen et al. (2026), from Prof. Vechev's SRI Lab at ETH Zürich (arXiv:2602.11988) — found LLM-written instruction files measurably reduce agent task-success and raise cost, because the model pads them with plausible-sounding rules the agent then over-obeys. The paper's own conclusion: describe only minimal requirements.

agents-md-facts is that conclusion, mechanized. It reads your repo and authors a minimal AGENTS.md from detected facts — your real build/test commands, your real entry points, the conventions your linters already enforce. Every line traces to something true in the repo. Nothing invented, nothing padded.

Use

npx agents-md-facts            # scan the repo → author/refresh AGENTS.md (non-destructive)
npx agents-md-facts --check    # CI / pre-commit: exit 1 if AGENTS.md is missing or stale
npx agents-md-facts --dry-run  # print what it would write; change nothing
npx agents-md-facts --stdout   # emit to stdout (for piping)

Non-destructive. It refreshes only inside <!-- agents:from-facts:start --> … <!-- agents:from-facts:end --> markers — anything you hand-write outside them is preserved. Re-run it whenever the code moves to keep the file true.

What it authors

A minimal, standard-conformant AGENTS.md: orientation · setup & build · tests · where things live · conventions · guardrails · definition of done · security. Target ~35 lines. Every line is a detected fact or a curated default; if a line resolves no real ambiguity, it's dropped.

See it authored across languages in examples/ — Node/TS, Python, Rust, Go — each fixture ships the exact AGENTS.md the tool wrote for it.

Keep it true in CI

Add the composite Action to fail the build whenever AGENTS.md drifts from the repo — so the file your agents read is never a stale lie:

# .github/workflows/agents-md.yml
name: AGENTS.md
on: [push, pull_request]

jobs:
  check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: Wolfe-Jam/agents-md-facts@v0.1.0   # runs `agents-md-facts --check`

Prefer a raw step? run: npx agents-md-facts --check does the same thing. Either way, re-run the tool locally and commit the refreshed file to go green.

Authored, not invented

The whole point: this tool doesn't invent an AGENTS.md — it authors one from what's true in your repo. That's the exact difference the research measured: minimal-from-facts helps; LLM-freewritten hurts. Author clean, and there's no bloat for a linter to catch later.

License

MIT James Wolfe · Built on the open AGENTS.md standard.