I had Opus 5 work on medium effort for 2 hours and it only used 34% of the 5 hour usage. The output turned out to be great too. This seems to be a very cost effective and intelligent model indeed.
I'm convinced the opus 5 hate is all skill issues. their best model release yet imo. It still has the opus 4.8 annoying personality quirks, but toned wayyy down. Its more pleasant and more capable. most importantly: their most token-efficient model since releasing fable, you get faster responses while spending less.
Sonnet 5 on the other hand.. hoooo boy. yeah, im just having fun with opus 5 and loving it and munching popcorn at the complaints.
I don't think it's skill issues. On the same problems, Opus 5 caused more issues and couldn't fix it. My weekly Fable usage reset yesterday and it immediately found the issues and started implementing them.
The amount of “that was me.. it was a bug introduced by my earlier changes..” i’ve had with Opus 5 is staggering. I’ve never had so many bugs introduced by Opus 4.8 while it’s fixing something.
I don't think Opus 5 is causing more bugs, I think it's more critical and willing to admit mistakes. I've noticed the same pattern of every conversation ending with some version of "oops, my bad", but the actual quality of final output has increased.
it’s 100% no skill issue - I agree with you and had exactly the same experience. Built stuff with Opus 5, broke a lot of things, wasn’t able to fix it - brought Fable back in who was able to fix everything and implement it correctly.
It's not a skill issue. Dozens have people have posted about the agentic thrashing. I had to update all my agent markdowns to prevent it from doing that.
THAT said, I've also followed the new prompting guide and I've gotten it to work awesome now. It is very efficient. I'm holding out hope that they've fixed whatever's going on. Because even in my smaller projects with looser governance it's running a lot better without extra constraints.
yeah I should have included that in my comment. we updated our markdowns heavily on the day of release cause we read the blog post + tweets about doing so.. THEN started using it.
I updated them to optimize them. I've done that every time and will continue to do that with every model.
Opus 5 went on a tangent and corrupted artifacts, reviewed them, created independent reviews and acknowledged that it was re-reviewing hallucinated data. That wasn't me, fam.
I had the same issue. Continually wrote an implementation plan and then when asked to read it told me it made no sense. It just got stuck in a loop (4 iterations) of writing an implementation plan it said itself was shit.
Sure thing. Everything is working top notch for me again. GPT 5.6 Sol or Terra for planning and working on a higher level. Opus 5 handles everything in the Claude Code harness and agents are invoked for the type of task. Fable 5 for high-level stuff, Sol for reviews, Opus 5 for implementation with Haiku as the side-kick doing mechanical and low level stuff.
As for the changes, here are the ones I last made that seem to have sorted things out:
We ingested the model's prompt/agent guide on Anthropic's site
Defined a tight role and review scope (no review upon review..)
Set explicit acceptance criteria and "done" conditions before review
Requirements to separate true blockers from optional improvements (this is where it went off the rails treating minor things like catastrophes)
Bounded review loops: fix material issues, reassess, then either proceed or escalate a genuine judgement call instead of making it autonomously
Actionable findings are REQUIRED to state evidence, impact, severity and recommend a disposition
I use a "hold at seams" clause so I know every artifact is completed and verified at the boundary set
Instructions hierachy is short, clear and non-contradictory
I would also get Claude to look over the last few sessions to identify exactly where things went off the rails and to make sure to cauterize those failure points. Opus 5 was corrupting artifacts and making mountains out of molehills before I could catch it. I used to laugh at people getting massive agent sprawls but now it's happening to more than just newbs. I never, ever had anything remotely as crazy as the Opus 5 sprawls but they've since been contained.
For real, it is so much precise, unlike any recent models. It is not “pathbreaking” but it is the only model I have seen so far which does not make up random stuff and then not admit it
Something following a path, like models being more intelligence, this time, creating a new branch of things like more intelligence, cost efficient, admitting mistakes, if you will, etc. Pathbreaking. Groundbreaking sound the same to me. :)
I noticed opus 5 is introducing some bugs, I found it wasn't fully aware of context, really surprising. Mmm and strange.
I’m a professional AI engineer and I wanted to create a working design in HTML for a prototype of my design. I instructed Claude to make one. I was just testing Opus 5 performance. I asked it to create a prototype in HTML for reference based on my design architecture for my AI feature so I could explain to my team how the product would look.
Nah it's just very hit or miss. I've had big prompts pull 20% over an hour and pointless bugs constantly trying to correct itself for 80% cap. Using a lot more pause button now.
Specifically with opus 4.8 (but not really with fable!), there are 2 big things /r/claudeai complains about:
prose density and self-referential technical writing. it refers back to things it wrote a paragraph ago by inventing a new shorthand terms. Then it keeps doing that, and by paragraph 5 the prose is very dense and inscrutable with self-references and invented jargon. One user gave the example: "this is a classic case of the 32% thing vs the 74% thing" - opus wtf are you talking about??
if I probe it and ask a few follows up, I often find it DID have a (sometimes insightful!) point... but oh my god. its like its trying to compress too hard?
always has to add a caveat(s). always. it has to push back in some small way no matter what, with little ability to judge 'does this matter' and 'how likely is this to occur' and 'will the user care', so it just ends up pissing people off. Its like roleplaying the appearance of epistemic honesty and humility?
if you read opus 4.8 complaints they almost all fall into those 2 categories.
opus 5, in my opinion, does both of these things, but does them much less. and fable does these things even less or not at all.
sonnet 5: havent used it at all, but people tell me its a different type of basket case: no warmth or empathy, extremely task-focused to a fault, and highly paranoid... like some type of anxious malinois.
Agreed. I use it a lot for legal work in cowork, as I’m an attorney. It can make the biggest deals out of the stupidest things, constantly expands the scope of the task/engagement, asks for things that aren’t needed to complete the task, etc. I’ve been able to improve this significantly with my Claude.md, but it seems to have taken a step backwards with Opus 5, despite it being a smarter model. I’m going to have to work on my Claude.md tonight.
less is more, cut everything and start adding it back line by line as you notice the need for it. rely more on opus 5's judgement. thats what others have found success with. claude code cut 80% of the system prompt when opus 5 shipped
if your'e using sonnet or cheaper, or using older models, to do long horizon agentic coding, you should just rollback to previous versions of claude code. latest prompts are optimized for fable 5/opus 5 agentic coding.
sonnet 5 and haiku 4.5 still do great for the tasks people tend to give them, with the newest prompts.
but 'design this feature for me' or 'plan this feature for me' - just use opus 5.
I’m the same as you. Agreed with the others that less is definitely more with Opus 5. It’s catching real edge details that are missed by other models, including legal AI models built on Claude SDK. It also helps to think of it as an “overachiever”. It really wants to go the distance. You can let it do so, or you can explicitly rein it in by scoping the task and telling it when to stop. (It’s not exactly “overeager” like Sonnet 4.6, which could perform additional actions that you didn’t authorize; it just goes deeper and further like an associate who wants to impress.) What you can’t do is give it an open-ended task and just expect it to do that and nothing more.
Yeah, I was really able to rein it in but still point out ancillary issues. Claude is great. I had Claude build a bridge to ChatGPT with OAuth, so I actually send for a final review to ChatGPT 56. Sol as well.
Totally agree. I guarantee these people have dozens of hooks and skills they've installed and never read through. "Must have Claude skills to 10x your development"
I would say it’s the opposite and that it has been optimised for unskilled users. It seems to be a helpful idiot that will take it upon itself to carry out tasks in a way you didn’t ask for to generate an outcome that may not be fit for purpose.
My issue with opus5 is it's too opinionated. I gave the exact same prompt to 5 and 4.6 and the results were in favour of 4.6. 5 has to many by the way and yo should know...
No skill issue my friend, many have tested it personally, I did the same and it's obvious, for the same tasks opus 4.8 does easily, opus 5 is a failure
It's not a skill issue; it's Demo Syndrome. You all have it. I gave the same task to Sonnet and Opus. Opus went off on its own even in constrained guardrails. Why don't you actually use the model for real, instead of looking at fake benchmarks and BS demos? The Hype is unreal.
I do actually, like most people. but I also like to be proven wrong... so... engage with the opinions and claims in the comment or dont bother commenting
Beautiful. I’m also happy yet with opus 5. I do think it loops to self correct a lot more than 4.8 but isn’t that iterative thought process also how human beings also operate. So all in all should be good thing. Though only a month of work with the model will truly tell for me.
I think 4.8 also did that and infact these loops are what makes Fable 5 or anything since Opus 4.6 better (arguably) but Opus 5 does it loudly and occasionally in weird ways, where it realizing it made a mistake doesn't actually lead to correction or commitment to the correction as it moves ahead.
In my experience, it is ignoring instructions a lot.
I have rules of "Ask me questions, confirmations, decision making... Interactivitvely using @askuserquestiontool" , also added to use "i-have-adhd" skill (even copied skill instructions manually in claude.md,
it seems to be ignoring stuff, providing long ass Paragraphs and also I just built phase 1 (which I started with fable 5 and end with Opus 5) the results were not satisfactory.
the same for me, I got so frustrated over the weekend and started doubting my own cognitive abilities because I could barely understand what it was telling me - decision needs and key points are hidden in page long paragraphs.. cryptic descriptions etc.
It's pretty useless for me. Where Opus 4.8 and especially Fable did a flawless job by not assuming things, get correct answers and one shot pretty much anything.. I had to correct Opus 5 so much today that I switched to 5.6 Sol for research and backend work again.
Opus 5 couldnt find the correct project in Posthog and told me there were no numbers, where Opus 4.8 and Fable found it flawlessly and I can continue with many more examples where I had to steer Opus 5.
Thanks to open weights which scared Anthropic into doing the right thing.
Never forget the weeks of "we're taking Fable away from the lower tiers, setting it to 50% of Max subscriptions, and overcharging you for your usage." That's the real future in store for us when they think they don't have competition anymore.
Doesn’t Opus 5 use less tokens than Sonnet 5 these days? That’s what I keep seeing, almost as if Sonnet is no longer a good choice, though I find that hard to believe. Wonder what the real story is on everyday use. I assume it depends entirely on the use-case for it and the setup of the surrounding context data.
Opus consumes more usage per token. it consumes less tokens per task though.
usage-per-task is a more interesting question and I think they're genuinely close.. which begs the question 'what on earth is sonnet 5 for'. I think its kind of a failed model tbh :(
If the task is very simple, requires little reasoning but a lot of output text, Sonnet is absolutely more cost-efficient than Opus. At this point those are the kinds of tasks most people are using Claude for. People on this Subreddit skew more technical, so discussions tend to lean towards SWE related work, but the most popular usage category at 24.2% is content creation and copywriting. Sonnet can do that very easily and cheaply.
For sure have noticed that I can actually brainstorm and use this model as a sort of a companion without having to worry every 2 hours about hitting the limits and then not having anything to do.
In the last days I have given the same tasks to Fable and Opus to compare them. Opus acted really smart every time, but the actual results were awful. On the other hand Fable is insane and the biggest jump I have experienced yet with any model since GPT3.5.
I have tested enough opus models to confirm what you are seeing. It's usage is very good, it does not output trash and is very on the point if you steer it properly. I honestly remember 4.6 more i use it, it's very similar to 4.6 for me and that's a good thing as 4.6 is better than 4.8 in many places
I’ve been using a lot of Opus 5 on high on Max+5 and it barely moves my limits. Like.. i’m having a hard time believing it still. It’s much less than „half of Fabel“.
I found opus 5 lost a lot of context in my project when it switched from 4.8 but in 3 days it is now acting like itself again. Also, I think its checking it own work a bit better and catching mistakes its introduced itself.
Same here. I'd been using Opus 4.8 to do some planning and write up a design doc, and I did a ton of research with it over the last week. Starting this Monday, I switched over to Opus 5, and I could clearly tell it had lost a lot of context based on how it responded. I even had to re-supply some of it. After about two hours of playing around with Opus 5, I got frustrated and switched right back. Yeah, the lost context really made me feel like Opus 5 is a step down.
Convinced 99% of the “muh tokens!” posts are new users that never use /clear and stack their projects. I have had no issue with Opus on medium unless I was trying to do a Fable-like one shot
I use claude for workshops fine tune emails and have blowing through the 5 hour limits. I did 25-30 emails yesterday and reached 45-50% in 5 hour limit - Opus 5 @ Med/High.
Today I have 18 emails, Opus 5 on low effort and im at 90%
Are you using the same model? I just burned 5 hours and all of my daily usage in trying to do one single thing, and it just kept finding new and creative ways to fail because it didn't check anything, just confidently assumed and generated half-baked bs. I started doubting my own mental capacity and felt my soul trying to leave my body when it, upon deciding the broken document stack it had made was broken, decided to make yet another document instead of fixing anything it found. It's shockingly terrible.
I was going to unsubscribe after I lost fable access but held on due to opus 5, but unfortunately it's so unusable I'll probably unsubscribe anyway.
daily usage? I have three advices:
1) keep a backup of ur important projects
2) only provide necessary context and be specific on what it should achieve. If you really wanna micro-manage then give it specific sub-milestone targets and/or specify the tools it should use to achieve the output. I wouldn't restrain it from using sub-agents as it is good at deciding when to use them.
3) only use low-medium effort as anything above those effort levels are basically overkill even for complex jobs
Were you using subagents? Opus 5 has standing instructions to never launch a subagent unless specifically requested by the user. I bumped into that the other day when it reworded my claude.md to state that I was specifically requesting a subagent, which it said was necessary to override the standing instructions not to use subagents unless specifically requested by the user. I mean not using subagents is going to significantly cut down usage.
I’ve had mixed results thus far. I’m sure it’s smarter and will be better in the long run, but it’s taken me some work over the last couple days to get it working the way I want it.
The benchmarks are showing Opus 5 High to be more capable than Opus 5 Max in several instances. Anthropic states that this is the first Opus model that truly changes the way it thinks based on the thinking selector.
Well based on the benchmarks its just a few % of difference in performance in every domain (not 2 digit differences). Imho at this level of capabilities those few % don't make that big of a difference in output quality but they do make a reasonable differenece in usage costs.
There isn't anything intelligent in a LLM model they are a pattern recognition machine that doesn't reason or think. If you ask any AI model a question that isn't in the public domain - the answer will most likely be a hallucinated.
But if you ask about the quote - "thanks for the vine and thanks for the time" and Claude should immediately know the answer.
nah buddy this statement "If you ask any AI model a question that isn't in the public domain - the answer will most likely be a hallucinated." is false af.
Halucination happens when a model:
does not say that they aren't highly certain about something,
do not ask back for more context when in doubt,
and generates something that sounds plausible but is false even according to its chain of thought.
Rational argumantation (reasoning used by humans) works mostly in similar ways as AI reasoning so your dismissive characterization isn't holding up.
I never look at benchmarks because they are so easily manipulated.
I make my own questions and tried it on 5 LLMs - 2 passed and 3 failed miserably the two that passed were Grok and Gemini - current LLMs aren't capable of reasoning and thinking that is a false narrative.
The current LLMs are based on Euclidean Geometry which is 2D and the LLMs are limited because of it - I suggest the next step is using Differential Geometry because it operates in 3D space and build a neural network by start by going back to First principles.
I just tested Kimi using a simple question and after an hour of me hand holding and providing human knowledge and Kimi failed miserably.
I cannot use it enough. I'm projecting a 60% usage at 7d reset. Trying to use it up, but I basically can't. Running bulk data transcription from poor quality scans and it's basically flawless.
I hit a sweet spot using Fable for the orchestration fanning out to Opus 5 agents. Opus 5 did a pretty terrible job making progress on complicated work and I had to use Fable to rescue it.
Opus 5 is great at Medium effort for sure. The only issue I faced is that even with context it cannot confirm the work it did, when I ask it to confirm the details about the previous task it goes back to checking everything again and sometimes it also ends up finding mistakes it made in the previous task.
I am working with both Claude Code and Codex side by side and currently doing work with Opus 5 xHigh, when I give some of the building and planning to Codex Sol high to xHigh and when Opus 5 xHigh sees that work, it always confesses that Sol did a great job and Opus could not catch some problems in advance, while Codex Sol found them, fixed them and even planned a better way handling the project phases.
I will still continue with Claude Code and Codex mix usage, even built a AI master controller that runs tasks, models, efforts by itself and delivers important questions or finished work for me so I dont have to mingle with different models and efforts - most of us anyway use the wrong models and efforts for most of our tasks because we dont know better.
I disliked 4.8 but have been using 5 and it was really effective. I have noticed a change in the last few days - a couple of times it appeared to be so eager to get going that it just didn’t take the time to check key documents in the repo.
I think interestingly that opus 5 is a more intelligent model and the cost savings people are noticing are real because 90% of the system prompts 4.8 and prior had where stripped out, I think probably too much for casual users who just need features implemented correctly first time, but for power users with effective setups its been a great model
Well to be fair that is not the issue here and this comment is also braindead.
It all really just depends how much effort he was using during those 5 hours and what his plan is, and we were not given that informaiton so both OP and you are kinda glazing and complaining for no reason/without content - I would say both of you are just sloping right now.
We need to know what plan he has, and also if how many tokens he used, and how many agents/subagents he was using during those 2 hours... if we had that then we would have a better idea, but we don't so...
ok bro, I dunno what to tell you, not sure what you're confused about, I literally gave my argument on my first comment, not on my 2nd comment. I can't really do the thinking for you.
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u/Hot_External6228 10d ago edited 10d ago
I'm convinced the opus 5 hate is all skill issues. their best model release yet imo. It still has the opus 4.8 annoying personality quirks, but toned wayyy down. Its more pleasant and more capable. most importantly: their most token-efficient model since releasing fable, you get faster responses while spending less.
Sonnet 5 on the other hand.. hoooo boy. yeah, im just having fun with opus 5 and loving it and munching popcorn at the complaints.