The evals for my agent skills scored 0% for as long as I had records. Not low. Not noisy. Exactly zero, every skill, every run. And I believed it. For months I thought my skills were bad, because the number said so and the number never wavered. Then one night I actually read the harness. It had fallen back to the wrong auth token. Every call it made came back 401, and it quietly graded each one a failure. The skills never got a chance to fail on their own. I was not measuring them at all. I was reading a broken thermometer.

Real weakness is jagged

Here is what took me too long to see. When a system is genuinely bad, it scores 40% one week and 60% the next. It passes the easy cases and trips over the hard ones. It has good days. Incompetence has texture, because an incompetent system is still in contact with the world, and the world varies.

A flat number has no texture. A flat number means the measurement stopped touching the thing being measured somewhere upstream, and what you are reading is the instrument's resting state. Doctors know this. A heart monitor drawing a perfectly straight line does not mean the patient is calm.

Only a broken thermometer writes the same number every time.