ResearchResearch paperAgents & Tool Use · Safety & Alignment · Evaluation & Benchmarks1 source · Oct 15, 2026

ToolBottleneckBench: Measuring Tool-Agent Performance under Controlled Pressures and Fixed Harness Budgets

We present ToolBottleneckBench, a benchmark that measures tool-agent performance under controlled pressures and fixed harness budgets.

Key points

  • The success score of a tool agent reflects both its model and the budgets of the harness that runs it.
  • Synthetic enterprise tasks stay fixed while one pressure varies: the registered tool catalog, the visible tool menu, the certified workflow, or the encoding of returned records.
  • Across 21 model and harness configurations, the visible menu is the only one of the three pressures that act on the model with a large penalty, and this penalty tracks truncation at the completion cap.
  • We recommend reporting pressure effects with the harness budgets under which they were measured.

Sources (1)

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