In 2026, no single hallucination score exists. Relying on generic metrics...

https://sticky-wiki.win/index.php/Claude-Opus-4.5_at_60%25:_Why_Your_%22Hallucination_Rate%22_Is_a_Measurement_Trap

In 2026, no single hallucination score exists. Relying on generic metrics leaves you flying blind. Testing against HalluHard might show a 30.2% error rate, while Vectara HHEM offers a different lens