The anthropic/claude-sonnet-4-20250514 model achieved a hallucination rate of 10.3%, a factual consistency rate of 89.7%, an answer rate of 98.6%, and an average summary length of 145.8 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
• average summary length concept