Re-running the same agent task flips results: minimal harnesses are most stochastic

yb2698 · x · 2026-10-14

The author examined harness 'stochasticity': what happens if you re-run the exact same task N times with the same model and harness? Using TB-Lite tasks already run 3 times, they measured consistency across pass/fail flips, turn-count variation, and input-token variance. Minimal harnesses (ipython, pi) suffer most, while OpenHands is by far the most consistent — which the author attributes to its implementation after analyzing trajectories.

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