Prompt Engineering

Claude Fable is Live...and its INSANE!

Anthropic Fable 5 (Mythos) Explained: Benchmarks, Pricing, Safety Guardrails, and 30-Day Data Retention In this episode, I break down Anthropic’s biggest release in three years: Mythos, now generally available to the public as Fable 5 (with Mythos 5 as a less-restricted variant limited to Project Glasswing). I cover the standout Frontier Code benchmark from Cognition Labs where Fable 5 jumps to ~29% and later ~46% on the full benchmark, discuss how performance scales with higher reasoning effort (test-time compute), and compare costs versus Opus 4.8 and GPT 5.5/Pro. I explain the new safety classifier that routes some requests to Opus 4.8 (about a 5% false positive rate), the 1M token context window, claimed research wins like faster drug design and molecular biology hypotheses, and the controversial 30-day traffic retention policy. I also highlight rollout details for Claude/claude.ai subscriptions through June 22 and the shift toward “responsibility loops” in real workflows. https://www.anthropic.com/news/claude-fable-5-mythos-5 https://x.com/cursor_ai/status/2064394824313376787/photo/1 https://developers.openai.com/api/docs/pricing https://www-cdn.anthropic.com/d00db56fa754a1b115b6dd7cb2e3c342ee809620.pdf My voice to text App: whryte.com Website: https://engineerprompt.ai/ RAG Beyond Basics Course: https://prompt-s-site.thinkific.com/courses/rag Signup for Newsletter, localgpt: https://tally.so/r/3y9bb0 Let's Connect: 🦾 Discord: https://discord.com/invite/t4eYQRUcXB ☕ Buy me a Coffee: https://ko-fi.com/promptengineering |🔴 Patreon: https://www.patreon.com/PromptEngineering 💼Consulting: https://calendly.com/engineerprompt/consulting-call 📧 Business Contact: [email protected] Become Member: http://tinyurl.com/y5h28s6h 💻 Pre-configured localGPT VM: https://bit.ly/localGPT (use Code: PromptEngineering for 50% off). Signup for Newsletter, localgpt: https://tally.so/r/3y9bb0 00:00 Mythos Becomes Fable 00:54 Frontier Code Breakthrough 03:01 Reasoning Effort Scaling 05:20 Safety Classifier Guardrails 06:41 Pricing And Context 07:53 Science And Cyber Risks 09:40 Data Retention Backlash 10:48 Access Rollout And Paywall 12:21 Third Era Of AI Loops