Rumor: Claude launches Fable 5.2 and Mythos 5.2, Xhigh tier beats Opus 5.5 at half the cost
FinanceYF5 · x · 2026-11-10
Account FinanceYF5 claims (unverified; naming inconsistent with Claude's actual lineup) that Claude simultaneously released Fable 5.2 and Mythos 5.2, targeting hard technical projects:
- Allegedly beats Opus 5.5 on nearly all evals, with some tasks at half the cost; up to 30% faster output than 5.1
- In FrontierCode 2.0 early tests, Fable 5.2 at High effort matches Opus 5.5 at Max effort for half the cost; Xhigh tops all tested public models
- Attached charts show score-vs-cost curves for agentic coding, agentic search (WANDR), and hardware engineering (BenchCAD 2.1)
- Safety: claims parity or better on alignment metrics, externally tested by AI Security Institute, FrontierDesign, METR
- Claude and Claude Code default to Medium effort
Related event: Claude Fable 5.2 Benchmarks Leak, Sparking Hoax Debate(18 posts)→
More from Models
- Claude Fable 5.2 tops VIALS-AA science visual reasoning benchmark at 67% with heavy tool use — ArtificialAnlys · 2026-11-10
- Dev builds a mobile game with Fable 5.2 as a Claude Artifact in under an hour — ChrisGPT · 2026-11-10
- SpaceX says Grok detects aerospace foreign object debris with 99.9% accuracy vs humans' 94% — elonmusk · 2026-11-10
- Fable 5.2's first ASCII backrooms art is so good people suspect it's programmatic — repligate · 2026-11-10
- Community pushes AI labs to publish system cards as machine-readable jsonl data — scaling01 · 2026-11-10
- ARLoop: fully-open 1.2B looped transformer beats Huginn-3.5B and Qwen3.5-2B on all 8 benchmarks — hhsun1 · 2026-11-10