Why did Anthropic warn Fable 5 comes with risks?

Anthropic is releasing Fable 5 publicly while warning it “comes with risks” because the model is derived from its Mythos-class capability. The company says it uses guardrails and “invisible safeguards” (such as prompt modification and other steering/constraint approaches) to limit effectiveness for dangerous requests. It also describes fallback behavior through conservative safety classifiers that can route some sessions away from Fable 5. The result is that Anthropic wants broader availability, but with mitigations meant to reduce misuse—hence the explicit risk framing.