LLM leaderboards are now often measuring the harness too, Gary Marcus warns

GaryMarcus · x · 2026-07-22

Gary Marcus amplifies a point that matters for model evaluation: teams have quietly shifted from benchmarking LLMs alone to benchmarking LLM + harness, while keeping the same leaderboard labels.

The core complaint is methodological: if the system under test changes but the benchmark name does not, comparisons become misleading. Marcus says this is important and people need to understand it to grasp what is happening in the field.

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