Artificial Analysis@ArtificialAnlys · XAnthropic 推出 Claude Fable 5，为首个公开可用的 Mythos-class 模型。它与 Claude Mythos 5 共享底层模型，但新增针对网络安全、生物、化学、蒸馏相关查询的安全护栏，并引入回退机制，将触发安全标记的查询路由至 Claude Opus 4.8。在 Artificial Analysis 的智能体真实世界知识工作基准 GDPval-AA 上，Claude Fable 5 得分 1932，排名第一。自适应推理 max effort 配置下，仅 2% 任务触发回退（Anthropic 称平均少于 5% 会话）。完整基准测试待公布。
Anthropic has released Claude Fable 5， the first publicly available Mythos-class model that ranks #1 in our agentic real-world knowledge work benchmark GDPval-AA
Claude Fable 5 shares the same underlying model as Claude Mythos 5， with added security guardrails for potentially harmful cybersecurity， biology， chemistry， and distillation-related queries. The release also introduces a fallback mechanism， allowing Claude Fable 5 to route flagged queries to a second model such as Claude Opus 4.8.
@AnthropicAI shared access with us ahead of public release to benchmark this model. Claude Fable 5 scores 1932 on GDPval-AA， our benchmark for agentic real-world work tasks， taking the #1 position and putting Anthropic models in 3 of the top 4 spots. The result was measured using adaptive reasoning at max effort， with Claude Opus 4.8 configured as the fallback model. Fable 5 falls back to Opus 4.8 on 2% of GDPval-AA tasks， with Anthropic stating that fallback occurs in fewer than 5% of sessions on average.
Full benchmarks for Claude Fable 5 are in progress - we will share the full Intelligence Index and publish scores on our website shortly