--- title: "Writing a Good AGENTS.md" url: https://daily.dev/posts/writing-a-good-agents-md-jzlmwgfoi source_url: https://www.philschmid.de/writing-good-agents type: article source: "Philipp Schmid" published: 2026-05-31T07:41:14.772Z updated: 2026-05-31T08:31:09.239Z tags: ["devtools", "llm", "ai-agents", "prompt-engineering"] reading_time: 3 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Writing a Good AGENTS.md **[Philipp Schmid](https://daily.dev/sources/philschmid)** · 3 min read · 0 upvotes · 0 comments ## Summary AGENTS.md (or GEMINI.md) files are injected into every coding agent session, making them high-leverage but also high-risk. Research from ETH Zurich shows auto-generated AGENTS.md files reduce task success rates by ~3% while increasing inference costs by 20%+. Human-written files only marginally improve performance (~4%) and still raise costs. Key findings: codebase overviews don't help agents navigate faster, tools mentioned in AGENTS.md get used 160x more often, and agents can follow ~150–200 instructions but the harness already consumes ~50. Best practices: keep it under 300 lines (ideally under 60), include tech stack, project purpose, and non-obvious build/test tooling. Avoid directory listings, code style rules, task-specific instructions, and auto-generated content. Use progressive disclosure by pointing to separate task-specific docs rather than embedding everything. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Stop Using /init for AGENTS.md](https://daily.dev/posts/stop-using-init-for-agents-md-nm6yotsrj) · Addy Osmani · 75 upvotes · 5 comments --- Tags: [#devtools](https://daily.dev/tags/devtools), [#llm](https://daily.dev/tags/llm), [#ai-agents](https://daily.dev/tags/ai-agents), [#prompt-engineering](https://daily.dev/tags/prompt-engineering) [View this post on daily.dev](https://daily.dev/posts/writing-a-good-agents-md-jzlmwgfoi)