ETH Zurich tested AGENTS.md context files against coding benchmarks and found the file splits cleanly in half: specific tooling instructions change what an agent actually does, while the repository architecture tour almost every generated file leads with never measurably speeds up how an agent finds code, and still adds more than 20% to the cost of every run. A second study, tracing 557 real agent sessions and over 33,000 pull requests, finds agents reach for instruction files on their own far more than technical documentation or API references.
The hosts work through where the two studies agree and where they don’t — including the sharp disagreement over whether reading documentation makes an agent test more or less afterward — and end on one engineer’s practical fix: start from an empty AGENTS.md and add a line only when an agent repeats a mistake you watched it make.