{"slug": "fable-5-1", "title": "Fable 5.1", "summary": "Anthropic released Fable 5.1, a new AI model that sets a standard on benchmarks, scoring 52.6% on Terminal-Bench-Science 0.1 (more than double Fable 5) and 55.8% on Terminal-Bench 4.0 versus 42.0% for Fable 5. The model also offers lower costs, with cache reads 75% cheaper and overall cost reductions of 25% for typical workloads and up to 45% for agentic ones. Anthropic introduced Enterprise Frontier Safeguards (EFS) for complete privacy, rolling out in phases starting this fall, and improved safeguards, reducing benign request flags by 60% and fallback rates on biology/medical questions by 85%.", "body_md": "Fable 5.1 excels at complex, long-running tasks. And its research capabilities offer an early glimpse of how AI models will contribute to scientific progress.\n\nAcross our benchmarks, the model sets a new standard.\nIt scores 52.6% on Terminal-Bench-Science 0.1, more than double Fable 5. On Terminal-Bench 4.0, it scores 55.8% against 42.0% for Fable 5.\n\nAs well as being capable of much higher performance than Fable 5, it can also achieve similar or better results at a much lower cost when set to lower effort levels.\n\nCache reads with Fable 5.1 cost 75% less than Fable 5’s.\nThis reduces the cost of the model in practice by around 25% for typical workloads, and up to 45% for highly agentic ones.\n\nWe’re also introducing Enterprise Frontier Safeguards (EFS), which give enterprise customers complete privacy (the same as zero data retention), while still being state-of-the-art at preventing adversarial use. EFS rolls out in phases, starting this fall.\n\nFinally, we’ve improved our safeguards. Our cybersecurity safeguards now flag benign requests about 60% less often.\nOn basic biology and medical questions, we’ve recently reduced the fallback rate by around 85%.\n\nClaude Fable 5.1 is available everywhere today. Claude Mythos 5.1, our model for cyberdefenders and life scientists, is available through trusted access programs.\nRead more:", "url": "https://wpnews.pro/news/fable-5-1", "canonical_source": "https://twitter.com/claudeai/status/2094848572143407483", "published_at": "2026-09-01 18:09:44+00:00", "updated_at": "2026-09-01 18:23:23.635999+00:00", "lang": "en", "topics": ["artificial-intelligence", "large-language-models", "ai-products", "ai-safety"], "entities": ["Anthropic", "Fable 5.1", "Fable 5", "Claude Mythos 5.1", "Enterprise Frontier Safeguards"], "alternates": {"html": "https://wpnews.pro/news/fable-5-1", "markdown": "https://wpnews.pro/news/fable-5-1.md", "text": "https://wpnews.pro/news/fable-5-1.txt", "jsonld": "https://wpnews.pro/news/fable-5-1.jsonld"}}