TraceLite AI releases TraceTrial-Bench: a benchmark that evaluates AI agent harness reliability across seven components with 95 tasks and reports macro-averaged harness scores from 59.8% to 72.0%

TraceTrial-Bench measures how reliably agent harnesses work, showing many tasks succeed even when a harness criterion fails.

HeyHomees Lab Notes · No. 10 · TraceLite AI · Published October 27, 2026

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In 30 seconds

What is it?

TraceTrial-Bench is a benchmark that evaluates AI agent harness reliability by organizing harness behavior into seven components (context, execution, governance, lifecycle, observability, tools, verification) and testing them with 95 expert-level, mechanism-oriented tasks.

How does it work?

The framework runs each task with a model plus a harness, captures execution traces via a Trajectory Tracing module, gathers evidence from the agent, harness, and environment with a Multi-source Evidence Acquisition module, and then attributes failures using a Failure Attribution module that separates agent performance from harness reliability.

How well does it do?

Across 4 harnesses, 9 models, and 95 tasks, the evaluation of 3,420 runs yields macro-averaged harness scores from 59.8% to 72.0%; Claude Code achieves the highest Agent Pass rate (44.0%) and OpenClaw the highest Harness Macro (72.0%). Only 8.4% of runs pass every criterion in both layers, while 31.1% succeed despite at least one harness failure.

What does it need to run?

The benchmark requires Python ≥ 3.11, Docker, and a Linux-style shell (or WSL on Windows). Users must provide a model.toml file with provider endpoint, model identifier, and API key.

By the numbers

The honest read

The reported macro-averaged harness scores (59.8%–72.0%) and pass rates are self-reported by the TraceLite AI authors based on their own benchmark runs. The figures show how often harness criteria are met, but they do not measure absolute task quality or real-world impact beyond the 95 curated tasks. The benchmark also notes that a sizable share of runs (31.1%) succeed even when a harness fails, indicating that the harness score alone does not fully predict task success.

What we don't know yet

Sources

Researched and drafted with AI from the sources above; every figure is checked against them by code before it is published, and a line that fails is dropped.

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