Dan Shipper@danshipper2h ago

BREAKING: Anthropic just dropped Opus 5.5—and it’s pulling some of our recent Codex converts back to Claude. We’ve been testing it at @every across coding, design, writing, and knowledge work. It sometimes beats Fable 5.1 in our testing and is up to 40% cheaper than Opus 5. It's a strong contender for new daily driver model: It’s excellent at end-to-end builds that match your taste. I’ve started reaching for Opus over Fable on big, end-to-end coding projects. And @kieranklaassen is replacing Fable 5.1 with Opus for his day-to-day product work. He calls it his new favorite model. It produces legible prose, but still trails Astra on writing tasks. Opus 5.5 scores a 68.42 on reading ease—the highest on any model we've tested. But in my writing benchmark tests it consistently buries the main point in intro paragraphs, and revisions. You'll be able to understand what this model is saying (yay!) but for day-to-day writing it's still behind. The economics are striking. Anthropic says Opus 5.5 will cost $5 per million input tokens and $20 per million output tokens. That’s the same input price and 20% less for output than Opus 5’s $5/$25. Altogether it should save roughly 40% on costs than Opus 5. It still has a “do the most” problem. @hammermt tested it on our standard knowledge work benchmarks, and it's results were great when thye came back. On at least one test it ran past the 10 minute time limit before delivering. Net Result: If you build apps and interfaces, try it. It’s become my go-to for ambitious coding projects. I’m still roughly 80/20 Codex versus Claude in day-to-day use, and I still prefer Sol and Astra for editing. But I’m spending far more of my tokens with Claude than I was a week ago. State of Play: Codex is still the better harness for me, but Anthropic is steadily gaining ground. They have a history of making their smaller models perform better than their bigger ones (Sonnet 3.7 for example) and they seem to have done the same with Opus 5.5. Full vibe check will be on @every soon!