explainx / blog
Anthropic launched Claude Fable 5 and Mythos 5 June 9, 2026 — SOTA autonomy, coding, and safeguards. Live again July 1 after export controls lifted June 30.
May 29, 2026
Claude Opus 4.8 delivers measurable improvements in agentic benchmarks, achieves 69.2% on SWE-bench Pro, and is 4x less likely to let code flaws pass unremarked. Fast mode is now 3x cheaper.
Jul 22, 2026
The largest copyright recovery in history is final: $3,000 per pirated book, split between authors and publishers, plus a legal fee cut from $187.5M to $101M. Training on books stays fair use — buying or pirating them doesn't.
Jul 20, 2026
A July 19 X thread revived "common knowledge" that Claude Sonnet is 1T params, Opus 5T, Fable/Mythos 10T. explainx.ai maps Musk's corroborating Grok ratios, unexcitedneurons throughput estimates, Kimi K3 benchmark paradox, and why Anthropic still publishes zero official counts.
Update — July 20, 2026: Viral X thread claimed Fable/Mythos ~10T parameters — unverified; Anthropic never discloses counts. Parameter debate + Musk ratios →
Update — July 7, 2026: Fable leaves included subscription plans after 11:59:59pm PT; Anthropic aims to restore when capacity allows. Subscription billing guide →
