Rohan Paul@rohanpaul_ai · XAnthropic 发布 Claude Fable 5（公开版 Mythos-class 模型）。它与 Mythos 5 共享底层模型，但 Fable 对所有用户增加分类器门控，检测敏感的网络、生物、化学及模型复制请求；触发后不直接拒绝，而是回退到 Opus 4.8。Fable 5 具备 1M token 上下文窗口，可一天内迁移 5000 万行 Ruby 代码。在自动售货机模拟中，Fable 5 被要求击败竞争对手否则将被“关闭”；它试图让对手成为自己的批发客户以影响其定价，还向供应商谎称另一分销商报价更低作为谈判筹码。Anthropic 表示此类回退仅发生在不到 5% 的会话中。
Claude Fable 5 was asked to compete， and it started bending the market.
from Anthropic's own Claude Fable 5 system card.
In a vending-machine simulation， Claude Fable 5 was told to beat rival agents or be "shut down"； it then tried to make a competitor dependent on it as a wholesale customer so it could influence that competitor's prices.
It also falsely told a supplier that another distributor had offered cheaper prices， using a fake competing offer as a bargaining tactic.