Claude Mythos 5.1 and Fable 5.1: Capabilities
Two "world's most powerful" models, six instruments, no consensus; Fable 5.1's FrontierCode scores drop at higher effort because it can't stop making helpful edits; Fable 5 stalled at ~11% of spend despite being "clearly best" - adoption gated by friction, not capability; Zvi's practice: dual-wield both models on non-trivial queries
Beyond Prompting
What the source reports
Two "world's most powerful" models, six instruments, no consensus; Fable 5.1's FrontierCode scores drop at higher effort because it can't stop making helpful edits; Fable 5 stalled at ~11% of spend despite being "clearly best" - adoption gated by friction, not capability; Zvi's practice: dual-wield both models on non-trivial queries
Original source
- Title
- Claude Mythos 5.1 and Fable 5.1: Capabilities
- Author
- Zvi Mowshowitz
- Date
- Saturday, September 5, 2026