Arpit Bhayani on eval design: every eval must name the failure mode it catches
arpit_bhayani · x · 2026-10-19
Engineer Arpit Bhayani shares his mental model for designing evals: getting them wrong cuts both ways — too few misses important failures, while too many over-constrains the model, since each eval encodes an expectation about how the task should be done.
His test is simple: for every eval, ask which failure mode it catches. If you can't answer, it's probably constraining the model without protecting you from anything. He doubts a magic number of evals exists.
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