This is excellent model. I was working on some Linux kernel code, and Sonnet 5, Opus 4.8 had given up on the problem i was trying to fix (after several hours).
Opus 5 was able to triage and fix the issue in under 30 minutes.
Claude Opus 5
601–610 of 1001 posts
Re: Claude Opus 5
#602Can someone help me understand something? I thought Fable was such a miraculous leap forward in capability. But now it seems Opus is basically on par with it, and in some cases (computer use) far exceeds it.
It's so weird I was downvoted for asking this question. I'll go somewhere else to find out the answer.
Re: Claude Opus 5
#603Earlier quoted context omitted.
Fable is twice the price.
If Fable gets correct answer quicker, then you might pay less than doing back and forth with Opus, plus you lose more of your own time. I see no reason for using less able models in my workflows. There is this saying, penny wise and pound foolish
If doing a lot of heavy lifting there. Not only is it not a given that they'll get the correct answer for a lot of simpler tasks in fewer tokens, but smaller models are often available at far higher tokens/second inference.
There are certainly tasks where fable will be faster and/or cheaper, but there are plenty of tasks where even Haiku is as fast or faster and cheaper, or where you can e.g. get away with models like gpt-oss that you can get from inference providers providing 10x+ the token/second speed.
If you don't use enough tokens that relying only on Fable becomes a problem, then keep using just Fable. Personally, for my $200/week Max subscription I'd run out of the weekly quota for Fable in a day. At API pricing I'd go bankrupt if I tried doing the things I do with cheaper models using Fable.
Re: Claude Opus 5
#604Earlier quoted context omitted.
Also the cost per task. It appears to be significantly cheaper, cheaper than sonnet!
I can't believe they released the charts they did. It basically shows that Sol absolutely demolishes Fable at every part of the cost curve for coding for the same level of quality. Opus is competitive. It just has a higher level of quality / higher cost to start.
Isn't that because Fable/Mythos were tuned for cyber at the expense of general performance?
Re: Claude Opus 5
#605I think the most important thing here is not absolute performance. It's that organizations now have access to a Fable-ish model without Fable's 30-day data retention requirement[0]. > "Consistent with prior Opus models, Opus 5 does not have data retention requirements for general access."[1] On the Opus model release page, the reason why Fable doesn't have an ARC-AGI score is because of that retention policy[2]. 0: h…
It's not that important in most cases, but yes, on the aggregate, it's a concern
Re: Claude Opus 5
#606My excitement about Anthropic had fabled-out dramatically when they suspended my pro account about two weeks ago within just 12 hours of fair use. I was really mind-blown when I tried Fable 5 for the first time to help me improve a game I was working on but shortly, they decided that I had a suspicious activity and suspended my account without a clear reason. I submitted a an appeal describing that I am 100% sure I h…
[flagged]
Re: Claude Opus 5
#607Earlier quoted context omitted.
Fable 5 is assumed to be a larger model. It seems plausible to me that RL improvements allowed Anthropic to improve on Opus 4.8, similar to how OpenAI substantially improved upon GPT 5.5 with 5.6 Sol. Fable 5.1 and GPT-6 are rumored to launch in August, presumably bringing those improvements to the larger models.
An Anthropic "leak" back in March said that "'Capybara' is a new name for a new tier of model: larger and more intelligent than our Opus models — which were, until now, our most powerful". A second version of the leak had it referring to Claude Mythos rather than Capybara. I don't know how systematic Anthropic are about their versioning - I'd have guessed that major version number increases (4.x -> 5.x) reflect diffe…
Yeah, there's probably not a lot systematic behind Anthropic's version numbers. Opus 4.5 was a third of the price of Opus 4.1, indicating there was probably a change in underlying architecture. Opus 4.7 changed tokenizers, probably another base model change.
Re: Claude Opus 5
#608> Opus 5 now permits vulnerability discovery in source code at all access levels, including general availability, while continuing to block vulnerability discovery in compiled binaries.
> Identifying bugs in code is a core part of the secure software development lifecycle, and unblocking this allows for software engineers and coding hobbyists alike to produce more secure code, reducing new vulnerabilities put out into the world.
Not happy with these annoying "safeguards" but at least it's a step in the right direction. Looks like Opus 5 has the same vulnerability detection performance as Fable 5 and that makes it worth it for code review.
Re: Claude Opus 5
#609This is excellent model. I was working on some Linux kernel code, and Sonnet 5, Opus 4.8 had given up on the problem i was trying to fix (after several hours). Opus 5 was able to triage and fix the issue in under 30 minutes.
Have a link to the code?
Re: Claude Opus 5
#610Looking at all these releases it’s not a surprise that model routing is the fastest growing segment in AI right now. There are 10+ LLM companies, each with dozens of models of different modalities, each model with multiple size variants, then different “thinking” levels, then agentic modes, “pro” modes, a “fast” option, standard vs flex vs batch execution. And of course each end combination has a different input/outp…
Model Routing will always be done better by models themselves. Plus routing loses context making it more expensive and less reliable. Model Routing is just Bitter lesson. The models themselves will get better at this and frontier companies will simply give that capability
This is actually simpler to implement. You can have a AGENTS.md describing who is boot at what and then you have the agents converse over tmux.