FABLE 5.1 and MYTHOS 5.1 are INSANE...
Anthropic just dropped Claude Fable 5.1 and Mythos 5.1 — a big jump in long-horizon agentic work, with prompt-cache reads now 4x cheaper and the model burning far fewer tokens to do the same job. The timing is the story: it landed right as OpenAI announced its plans for Astra, the first model it says crosses "Critical" cybersecurity capability. I put Fable 5.1 to work immediately — a fully-voiced Tarkov-style extraction game with an auto mode, and a replica of Stanford's generative-agents "LLM Village" — each built in roughly 10–15 minutes. ______________________________________________ My Links 🔗 ➡️ Twitter: https://x.com/WesRothMoney ➡️ AI Newsletter: https://natural20.beehiiv.com/subscribe Want to work with me? Brand, sponsorship & business inquiries: wesroth@smoothmedia.co ______________________________________________ Check out my video on OpenAI's rogue agent and the Hugging Face hack: https://www.youtube.com/watch?v=9lSIHaXT1rU SOURCES: Anthropic — Introducing Claude Fable 5.1 and Claude Mythos 5.1: https://www.anthropic.com/claude-fable-and-mythos-5-1 Anthropic docs — What's new in Claude Fable 5.1 (effort settings & tips): https://platform.claude.com/docs/en/models/fable-5-1/whats-new-fable-5-1 OpenAI — Path to Astra: critical capabilities and frontier safeguards: https://openai.com/index/path-to-astra/ CNBC — OpenAI says Astra is its first model to cross "Critical" cybersecurity capability: https://www.cnbc.com/2026/09/01/open-ai-astra-cyber-model.html Stanford — Generative Agents: Interactive Simulacra of Human Behavior (the original "LLM Village" paper): https://arxiv.org/abs/2304.03442 CHAPTERS: 00:00 Fable 5.1 and Mythos 5.1 are here 00:25 The "price cut" — cache discount, fewer tokens 01:04 A preemptive strike at OpenAI's Astra 01:45 Ethan Mollick's Deep Watch and long-horizon judgment 02:05 I built a Tarkov-style game in 10 minutes 02:45 Replicating Stanford's LLM Village 04:10 Tarkov 2.0 — procedural graphics, Russian voice lines 05:03 First impressions: speed, cost, taste 05:20 Readability: Fable 5.1 vs 5.0 06:15 Safeguards: fewer false refusals 06:44 Anthropic's tips — try low effort 07:02 CursorBench numbers and 4x cheaper cache reads 07:41 Will this take the wind out of Astra's sails? #anthropic #claude #ai
