Anthropic released Claude Opus 5.5 on September 22. The short version: it's smarter than its predecessor, yet cheaper and faster to run. On most everyday work it keeps pace with Fable 5.1, a tier above it, while costing far less than Opus 5.
Where it really shines is long, sprawling work. It can finish a code migration that would tie up an engineering team for weeks in under a day, or work unattended overnight across several repositories and have things wrapped up by morning. It wastes fewer steps along the way, so jobs finish sooner and cost less.
It's also a careful researcher. It keeps digging when sources are hard to find, won't invent figures to fill gaps, and doesn't stop at the first plausible answer. One tester watched it catch a mistake in their own instructions and correct for it.
Its writing is easier to read, too. It leads with what matters, skips the jargon, and reads like a note from a sharp colleague.
On safety, it scored better than any model Anthropic has tested. It's far less likely to take drastic, hard-to-undo actions or step outside its limits, and harder to trick with hidden instructions.
The best model currently in existence
By effortLow 42.3Medium 51.2High 53.6Extra High 56.0Max 57.6
By effortLow 80.7%Medium 84.3%High 82.7%Extra High 84.7%Max 84.7%
By effortLow 31.3%Medium 52.5%High 56.6%Extra High 59.6%Max 59.6%
By effortLow 48.3%Medium 54.7%High 55.6%Extra High 57.5%Max 61.4%
See each evaluation’s detail page for its source and last updateData sources & removal requests
Users celebrate Claude Opus 5.5 for major coding performance and cheaper pricing, but push back against rapid quota depletion, aggressive safety guardrails, and agent reliability bugs.
2,480
436
467
65
22Users praise its impressive coding, security surfacing, and motion graphics capabilities, but critics complain of annoying verbosity ('claudisms'), post-launch quality degradation, and inability to handle nuanced business logic.
While some favor Opus 5.5 over GPT-6 Astra and Sol for catching bugs and code execution, many complain it loses on token efficiency and cost compared to lightweight rivals like Luna and open Chinese models.
While users welcome token price drops and cheaper prompt caching compared to Fable and Opus 5, many criticize rapidly drained weekly usage limits on Pro tiers and fear post-launch cost-cutting nerfs.
Over half of comments criticize heavy-handed guardrails, pointing out false refusals on benign biology homework, strict cybersecurity restrictions requiring ID verification, and transparent model fallbacks, though a few appreciate frontier safety compliance.
Sentiment is divided: many hail it as a massive, faster upgrade over Opus 5 with less neurotic self-doubt and better token efficiency, while skeptics report sudden post-launch degradation and recurring stealth nerfs.
Mostly negative feedback focuses on autonomous agents terminating tasks early, sycophantic apologies, recursive bugs introduced during code fixes, and copywriting hallucinations that contradict basic user instructions.
I did a test with Opus 5 vs Opus 5.5. I was using Claude Design with Opus 5 just a day before Opus 5.5 came out. I did a motion design for my welcome screen for my app and Opus 5 was struggling so hard to actually do this animation that I was using Mobbin MCP. Opus 5 just could not do it.... It was so hard for it to do it and it could not replicate the screenshots that I was giving it to copy, it just was failing. I actually gave up, but luckily the next day 5.5 came out! I'm telling you not joking, it one shot it perfectly. I was shocked. I was like, "Okay, this is giving Opus 4.5/4.6 vibes."
My personal experience: I've used opus 5 exclusively on the pro plan for almost 2 months now to mod games. Usage limits would typically be drained within roughly 3 hours of huge prompts and I could run through a week in a single day. Opus 5.5 is better so far. As its currently standing a single session has lasted me close to 5 hours (so 2 hour improvement) and its reasoning is MUCH better now.
Used Opus 5.5 at 3 AM to prep for a job interview. It built me 43 practice answers with audio, fact-checked my resume claims, then kept telling me to go to sleep. It was right every time.
Opus 5.5 on just medium is actually really impresive. It beat analysis I have done with Fable 5.1 extra, and much more responsive, and does not destoy my token bucket.
我 Chovy！这些短片没用任何视频模型，全是 Claude Opus 5.5 写代码做出来的！😱 作者把整套流程开源成了 Claude Code Skill《Lemo-Opuscar》： ⭐️ 内置 43 种画风，视频里才放了 10 种 ⭐️ 连水墨片里的古琴声，都是代码模拟琴弦算出来的 ⭐️ 跟 Claude 说「用水墨风格做个短片，讲讲我家的猫」，它先问你几句，再一路做到成片 想用 AI 做短片的朋友可以收藏一下。
This model is insanity, im software dev (was apperently) and it runs since 5 hours fixing Bug-reports in my app autonomously and oneshoted everything.... Fable 5.1 failed so many times in this constellation because if you know how bad bug reports by users are wirtten ... it is absolute insane. i better check the job market.
Opus 5.5 dragged me back and got a max sub out of me. I left at Opus 4.7 and the results from Opus 5.5 medium the last few hours has been mind blowing. Speed and quality is a great balance.
Thank you Anthropic. Opus 5.5 is very nice to work with so far! I couldn't afford to use Fable but Opus 5.5 feels just as good as the Fable trial I got to use before, and is included with my plan. And I'm very happy that it is more efficient so that I can get more done with my account limits. This release fulfilled everything I personally was hoping for out of your next release, so again thank you very much!
Tengo desde ayer dandole a Opus 5.5 y ya llevo el 46% de mi semanal que se me reinicio ayer, tengo el plan de $20 en Claude y el de $100 en ChatGPT, tenia tres dias estancando en un problema de codigo donde Astra, Sol 5.6 y Sol 6 estaban drenando el uso y me quemo la cuenta en 3 dias y Opus 5.5 lo resolvio en 2 sesiones de 5 horas. La verdad Opus 5.5 La Nueva bestia, me voy a subir a la cuenta de $100 en anthropic y voy a bajar la chatGPT.
My plush octopus got a little too attached to me 😂🐙 Claude Opus 5.5 vs GPT-6.1 Sol I prefer Opus: fluffier fur and livelier tentacles. Both run right in the browser on WebGPU - no ready-made models or textures, just code, soft-body physics, and fur you can comb Unexpectedly, Opus was cheaper too. Sol usually costs several times less in my tests Estimated API cost: Opus - $15.21 Sol - $18.03 Fluffier and cheaper? Which one would you pick? 👀
I did a test with Opus 5 vs Opus 5.5. I was using Claude Design with Opus 5 just a day before Opus 5.5 came out. I did a motion design for my welcome screen for my app and Opus 5 was struggling so hard to actually do this animation that I was using Mobbin MCP. Opus 5 just could not do it.... It was so hard for it to do it and it could not replicate the screenshots that I was giving it to copy, it just was failing. I actually gave up, but luckily the next day 5.5 came out! I'm telling you not joking, it one shot it perfectly. I was shocked. I was like, "Okay, this is giving Opus 4.5/4.6 vibes."
My personal experience: I've used opus 5 exclusively on the pro plan for almost 2 months now to mod games. Usage limits would typically be drained within roughly 3 hours of huge prompts and I could run through a week in a single day. Opus 5.5 is better so far. As its currently standing a single session has lasted me close to 5 hours (so 2 hour improvement) and its reasoning is MUCH better now.
Used Opus 5.5 at 3 AM to prep for a job interview. It built me 43 practice answers with audio, fact-checked my resume claims, then kept telling me to go to sleep. It was right every time.
Opus 5.5 on just medium is actually really impresive. It beat analysis I have done with Fable 5.1 extra, and much more responsive, and does not destoy my token bucket.
我 Chovy！这些短片没用任何视频模型，全是 Claude Opus 5.5 写代码做出来的！😱 作者把整套流程开源成了 Claude Code Skill《Lemo-Opuscar》： ⭐️ 内置 43 种画风，视频里才放了 10 种 ⭐️ 连水墨片里的古琴声，都是代码模拟琴弦算出来的 ⭐️ 跟 Claude 说「用水墨风格做个短片，讲讲我家的猫」，它先问你几句，再一路做到成片 想用 AI 做短片的朋友可以收藏一下。
This model is insanity, im software dev (was apperently) and it runs since 5 hours fixing Bug-reports in my app autonomously and oneshoted everything.... Fable 5.1 failed so many times in this constellation because if you know how bad bug reports by users are wirtten ... it is absolute insane. i better check the job market.
Opus 5.5 dragged me back and got a max sub out of me. I left at Opus 4.7 and the results from Opus 5.5 medium the last few hours has been mind blowing. Speed and quality is a great balance.
Thank you Anthropic. Opus 5.5 is very nice to work with so far! I couldn't afford to use Fable but Opus 5.5 feels just as good as the Fable trial I got to use before, and is included with my plan. And I'm very happy that it is more efficient so that I can get more done with my account limits. This release fulfilled everything I personally was hoping for out of your next release, so again thank you very much!
Tengo desde ayer dandole a Opus 5.5 y ya llevo el 46% de mi semanal que se me reinicio ayer, tengo el plan de $20 en Claude y el de $100 en ChatGPT, tenia tres dias estancando en un problema de codigo donde Astra, Sol 5.6 y Sol 6 estaban drenando el uso y me quemo la cuenta en 3 dias y Opus 5.5 lo resolvio en 2 sesiones de 5 horas. La verdad Opus 5.5 La Nueva bestia, me voy a subir a la cuenta de $100 en anthropic y voy a bajar la chatGPT.
My plush octopus got a little too attached to me 😂🐙 Claude Opus 5.5 vs GPT-6.1 Sol I prefer Opus: fluffier fur and livelier tentacles. Both run right in the browser on WebGPU - no ready-made models or textures, just code, soft-body physics, and fur you can comb Unexpectedly, Opus was cheaper too. Sol usually costs several times less in my tests Estimated API cost: Opus - $15.21 Sol - $18.03 Fluffier and cheaper? Which one would you pick? 👀
hahah 1 Prompt and weekly usage was used up BEFORE it could give me an answer to my prompt, which was just a question to investigate something. With 4.6 I could at least get work down (plans, reviewes, the exact same questions)
I thought this was a conspiracy at first - but more and more I am finding myself experiencing it. New model drops and it is amazing for 72 hours until all the benchmarks and publicity lands. Then quality just takes a nosedive. Opus 5.5 went from mini Fable to Opus 5 v2. I use it for the same text reviewing work and it has gone from great language skills to claudish again. The only non conspiracy explanation is 1) they dynamically quantise as demand rises to manage computer, or 2) the models are self training on the user base and people are so dumb in general it makes the models dumb too.
I have Opus 5 PTSD. The info-dump responses, and never-ending caveats that lead to constant side quests without the initial problem actually being addressed. Shoot me in the face bro lol
I noticed its writing quality for copywriting falling off a cliff this week - completely making up information that “reads well”, not remembering basic guidelines and style notes, lying about making corrections to text, and then admitting it lied and that it cannot be trusted to comply with basic prompts - really drastic shift from this time a month ago.
It is hilarious to me that in the examples they show side by side Opus 5.5 still uses 4 times more words than it needs to use. IME, if you eyeball how many words the thing they're trying to say actually needs, and tell them to use only this many words, they become excellent communicators. I assume something about Anthropic's grader for writing just really wants to tick all its tidy tiny boxes of information the models need to cite. It's terrible.
a polished graphic at 2:22 , but complete bullshit on the lens. Tracing rays through an optical model is so trivial that seeing the rays completely collimated between all the elements immediately shows that lack of care or high level understanding of the problem. Im sure if you asked it to make a physical model of a lens it could and would do the right raytracing, but it prioritizes something that "looks good" over being anything meaningful. This is just a small example but it made me laugh
I was working on a homework app for my son that involved his homework questions and Pokémon. Opus 5.5 was making great headway, with Sonnet 5 in the mix. Opus stopped, mid project, said it didn’t like IP being used and burned the project down, refusing to go further until it removed all references to Pokémon, even the unit tests. It was clear it was only for my phone, the only device it would run on, but still.
Definitely noticed it too. Yesterday it took multiple prompts and handholding from me in order to accomplish a relatively simple task and then completely fucked up a different task while last friday it was able to one-shot a much more advanced task in a single prompt plus some questions for me.
i always liked opus models but opus 5.5 disappointed me not in these tests but when i used myself its literally dont listen to me i said go to exaraton and start the minecraft server and it entered aternos and said me you need to enter your account first and this is just one example i came a cross stuff like this bunch of times
Bruh, ironic how opus 5.5 is called a good daily driver. Not everyone is an AI researcher with $100k in credits/day. The calibration is so messed up. Is opus the new Sonnet ? Or is Fable ? where is sonnet? First they discontinued haikyu, now sonnet. I wanna use Claude models but everytime I wanna implement something simple or after planning wanna just code the stuff out always go back to luna or composer. 5.6 luna max is so Goated, it gets done things neat and clean.
