thats a really clever experiment. the fact that even an explicit “MUST call this tool” rule gets ignored kind of proves the point, its the same forgetting problem just with extra steps.
i agree hooks would be the real fix here. something that runs at the cursor level, not the model level, so it cant be “forgotten.” like how linters run after you save a file regardless of what the editor thinks. the model shouldnt be the one responsible for remembering to check its own work.
have you filed this as a feature request? i feel like your MCP test results would be a strong argument for it.