Claude Fable 5 released, built on Mythos model with added safeguards
English summary
Anthropic has released Claude Fable 5, which shares the same underlying model as Mythos but incorporates additional safeguards. Andrej Karpathy reports that benchmarks show state-of-the-art performance by a wide margin, and qualitatively the model represents a major version bump comparable to the step change from Claude 4.5. It excels in long, difficult problem-solving sessions, enabling users to tackle far more ambitious tasks such as generating explainers, dashboards, and custom single-use apps. The safeguards are currently overactive and may need tuning, and the model retains some quirks. Karpathy sees this release as a transformative shift that will dramatically increase demand for on-demand software creation.
Chinese summary
Anthropic 发布了 Claude Fable 5，该模型与 Mythos 使用相同的基础模型，但增加了额外的安全防护措施。Andrej Karpathy 指出，基准测试显示该模型以显著优势达到最先进水平，定性来看这是一个重大版本跃升，堪比以前 Claude 4.5 的进步。它在长时间解决高难度问题方面表现突出，允许用户执行更具雄心的任务，如生成解释器、仪表板和一次性自定义应用。安全防护目前过于敏感，可能需要后续调优，模型仍存在一些怪癖。Karpathy 认为此发布将推动软件开发的变革，极大刺激按需软件创作的需求。
Key points
Claude Fable 5 shares the same underlying model as Mythos but adds new safeguards.
Claude Fable 5 与 Mythos 使用相同基础模型，但新增了安全防护。
Benchmarks show state-of-the-art results with a large margin over competitors.
基准测试以明显优势达到最先进水平。
Qualitatively, it is a major version bump on par with the Claude 4.5 leap, especially for long, complex problem-solving.
定性评估显示这是一个重大版本进步，堪与 Claude 4.5 的飞跃相媲美，尤其在长时间复杂问题解决中。
The safeguards are initially over-triggered and will likely be tuned, while the model still exhibits some quirks.
安全防护初始过度触发，后续可能调优，模型仍有怪癖。
Enables generation of elaborate software artifacts (explainers, visualizers, dashboards, single-use apps), signaling a shift in software demand.
支持生成复杂的软件产物（解释器、可视化、仪表板、一次性应用），预示着软件需求的范式转变。