Anthropic Launches Claude Fable 5.1 With Lower Costs and Fewer False Positives

Anthropic today introduced Claude Fable 5.1 and Claude Mythos 5.1, which the company says are the "world's most advanced models for coding and knowledge work." According to Anthropic, Claude Fable 5.1 sets a new standard for coding, knowledge work, and long-running problem-solving tasks. It achieves similar or better results than Fable 5 at low or medium effort, and has much higher performance at higher effort tiers. It outperforms Fable 5, Opus 5, and OpenAI's GPT–5.6 Sol across multiple benchm