On Tuesday, Anthropic launched the latest versions of its flagship Fable and Mythos models. Anthropic promises that the updated models will offer stronger performance at a lower cost, largely because the company is reducing cache read pricing. Like before, Fable 5.1 and Mythos 5.1 are the same model under the hood, but while Fable 5.1 is now generally available, Mythos 5.1 remains restricted to Anthropic’s trusted access program because it features safeguards that Anthropic says are “specificall...