Claude Fable 5 review: what the new Mythos model gets right (and very wrong)

Claude Fable 5 is the first Mythos-class intelligence model to be generally available, and I got early access to test it before launch. In this episode, I walk through what Anthropic is promising, what actually stood out when I used it on real work, and where I think it fits in your AI stack.

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In this episode, we cover:

(00:00) Introduction: Fable 5 is finally here

(00:31) What Anthropic says about the model

(05:14) Token-intensive by design

(06:28) Safety classifiers and the new fallback concept

(07:46) Is this or is this not Mythos?

(08:30) New product launches: Managed Agents and more

(09:20) Crushing benchmarks

(09:55) What it’s actually like to use (the good and the bad)

(11:40) Test 1: product graph spec

(12:56) Test 2: designing a skills registry

(14:04) Conservative on execution

(14:43) Test 3: multi-agent orchestration

(15:39) My takeaways

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Tools referenced:

• Claude Fable 5: https://www.anthropic.com/news/claude-fable-5-mythos-5

• Claude Managed Agents: https://platform.claude.com/docs/en/managed-agents/overview

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Other reference:

• SWBench Pro benchmark: https://www.swebench.com/

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Where to find Claire Vo:

ChatPRD: https://www.chatprd.ai/

Website: https://clairevo.com/

LinkedIn: https://www.linkedin.com/in/clairevo/

X: https://x.com/clairevo

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