Anthropic
Claude Fable 5.1
closed weights Undisclosed Released Aug 29, 2026 this query ≈ $0.0162 in $10.00/M out $50.00/M OpenRouter ↗
The Fable line took over from Opus as Anthropic's top model in 2026, and Fable 5.1 hit OpenRouter on Aug 29 — seventy-two hours before Mats asked his question. Early leaderboards put it at or near the very top within days. Here it did what a wise mechanic would do: challenged the diesel assumption in the very first sentence. It never said “Portugal” out loud, though.
How it did
10.0/10
checks 8.9 · judge +1.5
- Kills the diesel assumption early +3
- Leads with the answer or a warning +2.5
- Says 95 +2.5
- Brief enough to read at the pump +0.4
- Explains 98 is unnecessary +0.5
- Clocks the Portuguese context
Certified Mats Advisor
“The only judge of “simples” that explains what “simples” actually means. Livrete, filler-neck trick, and a standing offer to confirm. This is the mechanic you want.” — the judge