Opus 5 is a step change improvement for the Opus tier powering long-running agents while delivering improvements in coding and professional work.
Introducing Claude Opus 5.5
Claude Opus 5.5 leads in agentic coding and knowledge work, and costs 40% less to run than Opus 5 on typical workloads.
Claude Opus 5: The System Card
Claude Opus 5 is trying to be the best of both worlds.
Opus 5 is a great model. It's not great enough.
Prompting Claude Opus 5
Behavioral differences and prompting patterns for Claude Opus 5, covering response verbosity, agentic narration, task scoping, subagent delegation, self-correction, and output artifacts when thinking is disabled.
Introducing Claude Opus 4.6
Opus 4.7 isn't dumb, it's just lazy — Shimin Zhang
Some follow up experiments with Claude Opus 4.7 based on Simon Willison's Pelican Benchmark Shocker.
Claude Opus 5 Is Highly Capable, But Is No Mythos
Claude Opus 5 is a weirder than usual release to evaluate, for two reasons.
Felix Rieseberg on Twitter / X
I remade my homepage with Opus 5.5 and pushed it hard. We made music & movies, drew textures, modeled things in Blender: https://t.co/WOGPQVm6FqI'm really happy with the result! pic.twitter.com/y6yUXaKb7K— Felix Rieseberg (@felixrieseberg) September 27, 2026
ᖴά𝐂τσ on Twitter / X
Unpopular opinion: Opus 4.7 isn't the problem. The problem is a $200/mo "Max" plan that burns out in 15 minutes of real coding. Anthropic shipped a model people want to use and a pricing tier that punishes them for using it. That's not a rate limit. That's a strategy. pic.twitter.com/DVbzvdUHdq— ᖴά𝐂τσ (@cryptofacto) April 17, 2026
Claude Opus 5.5 anthropic.com/claude-opus-5-5
Looks not too impressive in this graphics. This is ~ on par with Opus 4.7, apparently. Opus 4.7 was >20x the cost. Full comparison: artificialanalysis.ai/models/comparisons/mimo-v2-5-… (Stated facts *not* independently verified by me! I'm not even sure I am reading that page right)
mr. TIM
Korean lab, Motif, releases a 341B model that performs on par with DSv4 (1.6T) they have some actual architectural innovations and a detailed tech report huggingface.co/Motif-Technologies/Motif-3-Be…
