The anthropic/claude-opus-4-1-20250805 model achieved a hallucination rate of 11.8%, a factual consistency rate of 88.2%, an answer rate of 92.4%, and an average summary length of 129.1 words as of March 20, 2026.

Authors

• Person: Not available Organization: Vectara
  vectara/hallucination-leaderboard - GitHub

Sources

• vectara/hallucination-leaderboard - GitHub github.com Vectara via serper

Referenced by nodes (4)

• hallucination rate concept
• answer rate concept
• factual consistency rate concept
• summary length concept