Augment tests AGENTS.md: guidance can boost or break agents

A new post from Augment breaks down how AGENTS.md files impacted code-gen quality across its monorepo—sometimes improving results, sometimes making them worse. It shares what worked (tight, structured guidance) and what backfired. Read more at Augment: [https://www.augmentcode.com/blog/how-to-writ……

Augment tests AGENTS.md: guidance can boost or break agents

TL;DR

  • Augment evaluated how **`AGENTS.md`** guidance files affect code-generation quality in a monorepo
  • Results were mixed: some **improved agent output**, others performed worse than having no `AGENTS.md`
  • Effective files were **narrow, structured**, and easy to follow without drifting into unrelated material
  • Recommended patterns: **concise workflows**, decision tables, and selective examples from production code
  • Caution: overly broad architecture notes or long “don’ts” lists can trigger unnecessary exploration
  • Post also covers **measurement approach** and ways to reorganize existing docs for better agent results

A new post from Augment examines how `AGENTS.md` files appear to affect code-generation quality inside its monorepo, and the results seem to be mixed in a fairly dramatic way. According to the company’s writeup, some guidance files noticeably improved agent output, while others made results worse than having no `AGENTS.md` at all.

The broader lesson, as the post suggests, is that the best files are narrow, structured, and easy for an agent to follow without wandering into unrelated material. Augment highlights patterns such as concise workflows, decision tables, and selective examples from production code, while warning that overly broad architecture notes or long lists of “don’ts” can push the model into unnecessary exploration. The full post goes deeper on how the team measured those effects and how it thinks existing docs can be reorganized for better results.

Source: Augment

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