Claude Opus 5 beats Fable 5 — at half the hallucination cost
anthropic's claude opus 5 beats fable 5 on benchmarks and costs less, but its 50% hallucination rate creates a reliability dilemma for enterprises.
claude opus 5 achieved an intelligence index score of 61, narrowly beating fable 5's 60 and gpt-5.6 sol's 59, with particular strength in coding where it tied gpt-5.6 sol on the coding agent index. despite leading in capability, its hallucination rate climbed to 50% because it answers more frequently when uncertain, trailing fable 5 on the aa-omniscience factual accuracy test. pricing data shows opus 5 costs $2.03 per task on average, undercutting fable 5's $2.75, while lower reasoning tiers like 'high' offer better value than the expensive 'max' tier. this confirms that the frontier model race remains tight, with no single lab maintaining a clear lead.