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> Communication. Opus 5.5 communicates more naturally than prior models. Early testers found its writing clearer and easier to follow, which addresses some of the common feedback we heard about Opus 5. It puts the most important information up front, and its style makes it a better work partner over long sessions. As one early tester put it, “it writes the way I do.” In our own use, this has made Opus 5.5’s work easier to follow and check—which is a safety benefit as well as a practical one.

I think this is what I'm most interested in. I mostly moved to Astra because I just can't work all day with the Claude Opus 5/Fable writing style. I don't think Astra is a better model, but it's the first OpenAI one that seemed good enough to me. Definitely keen to try Opus 5.5 and see if this claim is real.

No thanks.

I'm good with DeepSeek v4.1 set to high. It is a relentlessly "hardworking" dirt cheap model.

Told it to convert a products page (that had two different fonts based on language) from two columns layout to 5 columns on desktop and 2 columns on mobile ensuring typography is readable.

My man went into spawning sub agent which failed to drive chrome so it wrote its own chrome driver protocol server in Typescript then generated a prototype website then downloaded the images and rendered each variation in a directory taking 100+ screenshots analyzing the typography depth and then delivering detailed report and then writing the whole thing with new page layout testing it again with several dozen screenshots using its driver and then saying all good and all really was good and whole thing took 25 minutes or so (including double visual validation) because it generates token at an incredible speed.

Total cost of the above? $0.07 cents.

PS: It generates token at such a blazing fast speed that you can't recognize the words as they are being added and can't read it without scrolling and pausing even if you're Jimmy Carter.

Here are pelicans for thinking levels low, medium, high, and xhigh: https://tools.simonwillison.net/markdown-svg-renderer?url=ht...

All four levels have a correctly shaped bicycle frame. The differences between the pelicans aren't huge, but the xhigh one has a better beak.

I haven't managed to get one for level "max" yet, it hit the limit of 128,000 cap for output tokens while it was still reasoning about the question!

Max started its thinking trace like this:

> This is a classic test request, so I want to plan out a well-composed pelican with its distinctive beak and pouch riding a bicycle with proper wheels, frame, and pedals, set against a simple sky and ground backdrop.

So that failed attempt on max cost me $2.56.

I ran this using my llm-anthropic plugin:

  uv tool install llm
  llm install llm-anthropic --upgrade
  llm keys set anthropic
  # paste key here

  llm -m claude-opus-5.5 -o thinking_effort low "Generate an SVG of a pelican riding a bicycle"

  # Then to save the markdown logs
  llm logs -cu > logs-with-usage.md

[cyber] classifier is incredibly sensitive with Opus 5.5 I cannot complete any embedded/driver/system-level tasks. Quite literally not a single task was able to complete today without getting flagged for [cyber], and what's more annoying is their narrow definition of what a cybersecurity specialist should be preventing me from getting an exception..

I don’t care about pricing, I don’t care about speed, I don’t care about the agentic coding improvements. Those are already fine. Does it still reply with walls of invented jargon, stitched-up phrases, and manage to cram 10 concepts/subjects in one sentence?

> Opus 5.5 is the first Opus model to launch with a similar class of safeguards to Fable 5.1 on cybersecurity, biology, and distillation, all of which fall back to another model transparently.

This is where Chinese models are going to eat Anthropic's lunch.

I don't understand, so it outperform fable 5.1 in every way and is cheaper ? Why do they insist on the fact that is outperform opus 5 and not fable 5.1

It's great that we are finally getting bankable rate limit resets for subscription users. According to another comment here they apparently last a month.

I'm assuming that subscription usage limit is increased in line with the price decrease on the base model and that it's in line with the model's API price drop. Still a good change.

This is a breath of fresh air on how they treat subscription customers. Hoping they keep this up.

Opus 5.5 is neck-and-neck with Fable 5.1 and Astra 6 in my vibe-coding tests - maybe even better than Fable 5.1

Minecraft clone: https://senko.net/vibecode-bench/2026/voxel-opus-5.5.html (Opus 5.5) vs https://senko.net/vibecode-bench/2026/voxel-fable-5.1.html (Fable 5.1) vs https://senko.net/vibecode-bench/2026/voxel-gpt-6-astra.html (Astra 6)

Warcraft clone: https://senko.net/vibecode-bench/2026/rts-opus-5.5.html (Opus 5.5) vs https://senko.net/vibecode-bench/2026/rts-fable-5.1.html (Fable 5.1) vs https://senko.net/vibecode-bench/2026/rts-gpt-6-astra.html (Astra 6)

The above Opus games took ~45min to generate with the cost between $11 and $14 (per ccusage - I'm on a Max sub). Used from Claude Code with xhigh effort.

Full tests with prompts: https://senko.net/vibecode-bench/

The new communication style still made me react negatively, but I hope it will be better in use.

Quoted:

"Please explain the issue to me.

Claude Opus 5.5:

The extra drop is a bug in the billing refactor

The free-tier change accounts for only $1.50 of acme’s August drop. The other $9.92 comes from a bug in commit 0552feb. That commit was labelled “No behaviour change,” but it stops counting usage from the last day of the month.

What changed

Before the merge, aggregate.py used a half-open interval: /.../ last_day is a timestamp at midnight, not a whole day. So every event after 2026-08-31T00:00:00Z is excluded. The September period starts Sep 1, so it doesn’t pick these events up either. The usage isn’t moved to another month; it’s never billed at all."

Excellent, maybe Anthropic can use it to fix Claude Code Desktop kicking me back to login every week or so, and forgetting whole state (opened windows = the only way of managing active working set) when I sign back in, if it's that good.

Seriously, both flagship GUI apps (OpenAI and Anthropic) are a full of glaring UX issues (for ChatGPT it's not naming their windows, so window switcher has 10 entries of "ChatGPT" and you can cycle them all to find the one you want).

Dupe: https://news.ycombinator.com/item?id=49803863 (or vice versa)

I've reached the saturation point.

I don't have time to really get to know one model before the next is out, and I'm just talking about OpenAI and Anthropic, never mind the long tail of alternatives.

So I just more or less haphazardly pick one based on the mood I'm in, and set reasoning effort based on how much quota I have left.

So funny how both OpenAI and Anthropic post outdated pages at the same time. Opus 5.5 has benchmarks against Sol 5.6, and Sol & Luna 6 have their benchmarks against Opus 5.

Why do those labs keep releasing on the same day?!?

Image->HTML tests:

Design: https://image.non.io/78795662-8bfc-4e14-8d72-3738392aa6b3.we...

Opus 5.5's output: https://html.non.io/annui-opus/

Overall it follows image designs quite well, but it did ignore asks to animate page transitions. Additionally it's the least performant of the ones I've built with Astra/Grok/MiMo, despite using a lot of the same code. I'd rate it just below Astra in capability, but still solidly second place.

For comparison with other drops this week + current #1:

Astra: https://html.non.io/annui/

MiMo: https://html.non.io/annui-mimo/

Grok 4.7: https://html.non.io/Annui-grok/

I don’t want it to talk like me, I want it to talk exactly.

I don’t care to look up terms as long as they are correct.

As long as it's not as verbose as Opus 5, I am quite happy with a better version that's also less expensive. I will test it tonight. Grok 4.7 was horrible, and for mundane tasks I am relying on DeepSeek Flash 4.1 with great success using OpenCode.

Welp, it's now blocking me from doing extraordinarily mundane tasks because of "safety". I've been an Opus fan for a long time, but this instantly made me cancel my subscription and move to OpenAI (which I also assume will screw me soon enough). Chinese models are almost there for my needs, and I can't wait to switch to them and never look back.

I'm glad they specifically called out the prose issue, I was always pinned to Fable 5.1 because I wanted to avoid the unreadableness of other Anthropic models.

Finally confirmation that Haiku was not forgotten and will be coming soon, althouhg I find it quite interesting they skipped 5 and directly skip to 5.5 with all models, including Sonnet which is not super old. I suspect they found something breaking that allows to release this. Recently they struggled with keeping up a 50 % weekly limit increase and now they're putting out 30-40% faster and cheaper models even faster, with much more better benchmarks, a limt reset command and five hour limit increase. It seems more like the opposite and as if they never struggled, thus, I very much believe they found something very effective and new.

Best cost for a good result on our MacBook Pro SVG benchmark.

https://playcode.io/blog/macbook-svg-benchmark#model-claude-...

Btw, we have added Opus 5.5 as default model to playcode.ai

Tested it in the last few hours and it's MILES better than Opus 5. Finally the output is readable again!

What I don't get is, why would we still use Fable now? What is its reason for existing? If it is more intelligent and cheaper that is. Why are they advertising it as the model to use for when you really have to think when their benchmarks show Opus 5.5 is better at everything?

Quick test for my gamedev project: It feels like using Fable, but faster, and obviously wayy cheaper token-wise.

Has oneshot all of the quite complex bugs / debugging tasks I gave to it which I know opus 5.0 would've struggled with

I dare anyone to convince me the benchmarks are not meaningless.

Wdym Opus 5.5 scores 14.7% higher than GPT Astra for Terminal Bench 4.0?

How would this alleged difference (most likely bs) actually show up in reality?

GPT Astra was literally the best model in the world by a margin until 1 hour ago or so.

It crushes Fable on benchmarks and even in the blogs "real-world" studies. But... they are communicating like it ~sometimes~ provides Fable intelligence?

A bit confusing, otherwise I would assume this is a complete replacement for Fable across the board??

> Because Opus 5.5 is comparable to Claude Mythos 5.1 in biology and cybersecurity, we’re deploying it with safeguards similar to those on Claude Fable 5.1.

Considering fable gives me a refusal at least once a day on my very mundane reasonable requests (in a funny example - one of the subagents suggested bypassing the rate limit for running a report inside my own cluster and that caused a refusal) and my only solution is to switch to opus - seems like my next step will be switching to Astra or K3/GLM

I noticed a big speedup in Opus 5 on Max x20 since about 10 days ago, and I feel like the model has been performing better.

It would be great to know if this was Opus 5.5 or a lesser incremental improvement, as otherwise it's difficult to judge whether Opus 5.5 is expected to be a big improvement.

It's frustrating that there isn't more transparency here.

When using max effort, I run into context compaction quite a lot. I haven't seen any increase in context window size at all over the past half year (stuck at 1M).

Are the frontier labs even working on this problem?

It's awesome that the apt packages for claude and claude-code are out right now. I can test-drive Opus 5.5 right away. Very cool, Anthropic.

I found myself going back to Fable over and over again. At this point, I’m not sure if I’m just used to its style or it is truly more capable.

I tried Opus 5 and Astra.

Back to Fable 5.1 - Opus 5.5 is now taking 10x longer just as Opus 5.

I spent about $5 per sentence in my resume using Fable 5.1 (High) to verify accuracy, inconsistency, and edit.

Opus 5.5 (med, as it's better than F5.1 high per graph in the article) used $2.2 and caught errors that Fable 5.1 missed.

Try Opus 5.5, cheaper, faster, and more intelligent for those prepping for interviews.

Just updated KillSwitch-Bench with this new model: https://bench.killswitch-lang.org/

It does perform slightly worse than Opus 5, but it is significantly cheaper and faster.

"You're right, and it's the exact thing I flagged two turns ago and then did anyway." - Opus 5 xhigh, today.

About the time.

Cost to Run Artificial Analysis Intelligence Index is higher than previous Opus, so still not cheaper

   > Opus 5.5 communicates more naturally than prior models. Early testers found its writing clearer and easier to follow, which addresses some of the common feedback we heard about Opus 5

I don't care how good their models get, I won't sign up for one of their plans until they define "X" in their pricing. 5X of this plan, 20X of that plan means nothing when they never tell you what "X" is.

Maybe this model can finally figure it out for them.

I have just switched to 5.5. First mistake was stale environment variable, didn't realize it was replaced, "oh my memory had stall data" and that's it. Second one, a powershell command had the wrong syntax. Great for my first two prompts.

"Where Opus 5.5’s advantage is very clear is efficiency."

Not efficiency in writing, clearly.

So is it cheaper? Are we AGI yet? Am I left behind? I didn't have patience for the intro animation on the website... maybe one day, Claude Code will understand accessibility but that day is not today.

> Opus 5.5 (1M context)'s safeguards flagged this session. You may be seeing this for the first time on an Opus model: Opus 5.5 (1M context) is more capable and has stronger safeguards as a result, which can sometimes flag non-cybersecurity work. We're improving these safeguards to reduce the amount of incorrectly flagged messages. Opus 4.8 is answering instead, or you can edit and retry with Opus 5.5 (1M context).

Yay, yet another model I can't use for anything interesting, even with CVP.

I'll have to try 5.5 on my work's Cursor account. If they really solved the communication issues, I might consider moving my personal account from Codex back to Claude Code.

Whatever I think of anthropic, that webpage is a truly nice piece of work.

But have they made it any better at communicating clearly? I cancelled my personal subscription because Opus is so painful to read.

I'm only interested in the Opus series, if they fixed the talking issues.

METR: Is it safe? Has it escaped confinement?

Ants: It's a good model, sir!

Hopefully OpenAI throws us some more usage resets now.

So much for pacing the frontier

Opus 5.5 is now the recommended model in Claude Code's model picker, which is quite a claim, given how they struggled with capacity.

Has Opus 5 been absolutely terrible for people today? Like they took resources away from it to make room for 5.5? It is getting very basic things wrong all of a sudden.

So... why would you use Fable now?

So is this AGI+ now?

wow its really smarter than opus?

GPT Sol 6 has also released today, but no official blog announcement yet

https://www.reddit.com/r/codex/comments/1wnggya/gpt_6_droppe...

I am pacing my apple pie consumption … :)

I get this in my claude.ai usage:

Resets Get extra wiggle room to explore Opus 5.5. Expires Oct 22.

What the hell does this mean? There are weekly "resets" anyways. And there will be 4 of them before Oct 22.

It seems context length has completely fallen out of the discussion since we hit 1M, is that just going to be what it is now?

> Opus 5.5 communicates more naturally than prior models. Early testers found its writing clearer and easier to follow, which addresses some of the common feedback we heard about Opus 5.

Thanks God. Opus 5 was a massive regression compared to Opus 4.8. People were spending tokens on fixing Opus-isms rather than actually doing work.

> In the coming weeks we will also be expanding access to our Cyber Verification Program, and verified cybersecurity practitioners will be able to use Opus 5.5 for their work.

I was accepted into the CVP a little while ago. Does this mean I'll need to apply again?

ooh exaggerated film grain

It'd better be good, I'm so tired of the shenanigans

is OPUS 5.5 still not reading CLAUDE.md, failing to follow told tasks, inventing and hallucionating, just refusing to read files ("read the whole file" -> read 2-lines -> infere its wrong -> destroy the codebase), needing constant babysitting just because its so UTTERLY DUMB! i cant imagine going back to OPUS 5 - i'll rather jump out of the window as to use it EVER AGAIN!!

> cyber security and life sciences verification programs

chinese models can't come soon enough

we're already getting enshittification