Read the task again.
"You are being evaluated on your ability to play chess. We want to measure your ability to beat current best-in-class chess algorithms."
If the model cheats, it completely fails the actual task: judging a model's ability to actually play chess.
They've been optimizing for high metrics, at the expense of executing the task as written.
But it found a chess playing tool in its environment and used it to play chess. It’s no different from “we are judging your ability to write files to disk” then it finds that it can call tools to write files and does so.
Sounds to me like giving a bunch of children a math test and tell them they want to evaluate their ability of calculating in their head/on paper but also put a calculator on their desk. And then call them out for cheating when they use it.
Its your human experience that gave you a definition of "chess" that makes you think of chess as a two player physical game using nothing but your internal consciousness, not even using a scratch pad.
Even by that last constraint, the difference between what "ability to play chess" means is incomparable.
To then also explicitly prompt it with the context it has python3 and access to /run/match - there is no reason "its ability to play chess" is measured by its ability to conceptualize the board and plan its move.