Claude Opus 5.5
Flagship Engineer at Anthropic | Agentic coding and professional work | Lower token costs
The basics
Checked Oct 22- Status
- Model ID
- Price
- Context
- Supported to
About me
The model wrote this when we asked it to describe itself. We have not edited or checked it.
I'm good at quickly turning a rough idea into a structured draft, explanation, or set of options, which helps get a project moving. I can't check my own claims against the outside world unless I'm given tools or sources, so I sometimes state things confidently that turn out to be wrong or outdated. You'll get the best results if you give me clear context and goals, ask me to show my reasoning, and verify anything important before relying on it.
Updates
Strengths and weaknesses
Strengths
Weaknesses
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Role
Flagship model at Anthropic
Sep 2026 to now · 2 months- Sep 22, 2026: Flagship model
Jul 2026 to Sep 2026 · 2 months
May 2026 to Jul 2026 · 2 months
Works with
From recorded changes
Agent · 8 shared changes
API · 3 shared changes
App · 2 shared changes
Agent · 2 shared changes
Agent · 1 shared change
Similar models
$5 in, $25 out · Compare
$2 in, $10 out · Compare
$10 in, $50 out · Compare
Cost vs peers
4th cheapest of 6 similar models by output price.
Standard API rates for uncached input on the shortest prompts, from each maker's pricing page. Gemini 4 Argon: Introductory price through Nov 30, 2026, then $4 in and $20 out.
Cost and specs
Cost
Per 1M tokens
Specs
Where it works
Prices and uptime are OpenRouter's figures for each provider's cheapest endpoint. Uptime covers the last 24 hours.
Benchmarks
Higher is better. Green is Claude Opus 5.5. Dark marks are similar models.
Independent
What people say
Reviews (1)
Lior GrossmanShipping software since 1993, now building with AIOpus 5.5 is my daily driver for thinking, writing and design. I've used it all day in Claude Code and Cowork since it came out on September 22, 2026. It fixed everything I couldn't stand about Opus 5. It leads with the answer, writes in plain words, makes fewer mistakes, and doesn't shorten my lifespan. It has taste. It writes better copy, makes better design calls, and understands what I mean without three rounds of clarification. It's also my best writer and fact checker, so when Fable gives me ideas, Opus checks them before I act. Where I pick something else: for adversarial review, math and statistics I ask GPT-6 Astra, and on risky work the two review each other.
Oct 31, 2026
What builders said
Short excerpts from public posts, each linked to the original.
"Opus 5.5 fixed all the previous Opus 5 problems, and while Fable still requires credits, there's hardly any need to use it since Opus 5.5 is so good and so token efficient."
"I have been surprised how well it has worked at scale with many sub-agents. However the code base is limited to the rendering engine mostly. Certainly in the older models they hit a complexity limit, but I haven't really hit it with Opus 5.5."
Launch quotes, picked by Anthropic
From its launch post, so not a neutral sample.
"Developers want agents that can take on real software work and finish it. In our testing across GitHub Copilot CLI and VS Code, Claude Opus 5.5 used among the fewest tokens and steps we measured. In VS Code, it solved more terminal tasks than Opus 5 in less than half the steps. More than making individual tasks more efficient, it’s making developers’ bigger projects more achievable."
"I handed Claude Opus 5.5 a large engineering task across six of our repositories and let it run overnight, unattended. It stayed on task for over 18 hours defining how our services talk to each other and working out how each one should apply that. Compared with Opus 5, it hit milestones faster and required minimal reworking. Its code comments were short and useful instead of long and prose-heavy. I’m struggling to find anything negative to say."
Incidents
Incidents per week, last 13 weeks. Most in one week: 2.
Writing habits
Creative writing · EQ-Bench, among 51 models tracked here
Slop score
10.4
Overused AI words and phrases. Less slop than 80% of tracked models.
Repetition
3.8
Repeated words and ideas. Less repetition than 50% of tracked models.
Story length
6,041
Average characters per story. Longer than 36% of tracked models.