What makes a good AGENTS.md?

Ben's Bites says AGENTS.md should keep only behavior preferences, not tech-stack maps or key files; the post cites a study saying that hurts performance and raises cost by 20%. It recommends symlinking AGENTS.md to CLAUDE.md, using conditional blocks, and relying on folder-level dynamic loading; the study name and setup are not disclosed. The real point is not more context, but smaller persistent instructions.

Why it matters: This is a practitioner explainer for coding-agent users, not a product launch. HKR-K and HKR-R pass on the concrete 'keep AGENTS.md small' claim, the 20% cost figure, and usable patterns; HKR-H is weak, and the cited study name and setup are not disclosed, so it sits at the low '