Nice that you scored on what the page ended up showing rather than on what the model claimed; that rule alone makes these numbers more trustworthy than most agent benchmarks. The Tessa Bright failure is interesting because the tool did exactly what it was told, so a cheap guard could be a pre-action echo for destructive buttons: return the target row's label alongside the element ref and let the model confirm before pressing. It would also be worth reporting the tool-list size as its own column, since 49k vs 3.2k tokens per call probably explains more of the time gap than anything about how the tools actually drive the UI.