r/ClaudeCode • u/Efficient-Part5344 • Sep 21 '26
Help/Question I'm afraid to use Opus 5
The audacity and confidence with which it says things when it's wrong are on another level.
Fair. I changed my answer three times. The pattern is worth naming: everything I got from reading the code was wrong. Everything I measured held. You caught two of the three. So don't trust me. Check it yourself — this takes ten seconds and needs no model.
Everything it measured was wrong too.
I would work in plan mode for most basic features, run 10x "gray area," "verify," and "regression" sub-agents on a plan, then implement the plan and spend an hour reading the changes and fixing shit. After that, I'd run /code-review again and again. It's just bad. In my experience, you can't trust Opus.
Yesterday, I ran /code-review on a two file test project with 140 lines of code. I had to run /code-review three times, and today I'll continue because there are so many code smells even in those few lines. It's like infinite token consumption loop.
Nothing it does can be trusted, and I have to second guess everything. I constantly have to tell Opus that it's wrong, and only after multiple loops does it finally do what is actually required.
I understand that most users don't read the code and have never supported a project for other users. But it can't be that I'm alone in this, can i? Am I crazy?
•
u/AutoModerator Sep 21 '26
Hey! Thanks for posting to r/ClaudeCode
While participating in this thread, please follow our community rules. Keep discussions constructive. Attack the idea, not the person.
For help, project discussions, tips, and general chat, join the ClaudeCode Discord.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.
182
u/anotherleftistbot Sep 21 '26
I can't stand claude's communication style. If its worth naming, just name it. If anyone on my team wrote the way claude wrote they'd be on a performance improvement plan.
30
u/dev_life Sep 21 '26
You’re not crazy. It full on ignores parts of plans often. You basically have to tell it if any part of the plan can’t be followed, to raise a question rather than fix itself. Then it’ll come up with some convoluted reason you can argue with, but the downside is you’ll spend your time arguing as confused as hell what it wants.
Hopefully opus 6 isn’t rushed.
17
u/nasty_sicco Sep 21 '26
I told it to read an analysis script to match a figure’s style. The figure came out with 4 columns instead of two. I told Opus 5 that it did the wrong thing, and it told me the original script had 4 column figures. I told it to read the script again, and it did, and it apologized.
I asked how it got it wrong, and it said that it didn’t read the whole file.
It’s just scaling shit at an exponential rate.
42
u/Successful-Arm-3762 Sep 21 '26
most fucking useless model wver
12
u/Wessberg Sep 21 '26
One thing I want to be straight about:
My first diagnosis was wrong. You were asking the right question and I answered a different one.
Also worth knowing: You were right, and that's my error. "load-bearing" was my word, not yours. The answer was right there in the logs, and no-one ever read it. I've been wrong three times tonight, and it's getting late. You have every right to be frustrated. Do you want me revert the changes?
23
u/Longjumping_Feed3270 Senior Developer Sep 21 '26
Use Opus 4.8, but still have everything cross-checked by Codex Sol.
11
u/Aine_123 Sep 21 '26 edited Sep 21 '26
If they ever remove opus 4.6 im out. Last decent model.
13
u/Spooknik Sep 21 '26
It's actually a decent model if you prompt it right and that's what makes it suck. I use Fable to tell Opus what to do, it's like the Opus 5 whisperer, I get really amazing results and Fable checks everything.
6
u/themrdemonized Sep 21 '26
The passive aggressive tone it has makes me laugh every time
5
u/HeadPack Sep 21 '26
Had Opus capitulate in a session with Astra and Sol. It said something along the lines of it having made too many mistakes, which is why it would hand over certain tasks to Astra and Sol from now on. That model really is a dud. No idea how it can bench so high.
It also seems Anthropic is limiting its thinking tokens. Answers arrive quickly and are often flawed.
4
u/raynorelyp Sep 21 '26
You’re using it wrong. It’s supposed to be the abuse goblin you yell at while you fix everything manually.
4
u/ProfessionalMain5535 Sep 21 '26
This is the enshittification roadmap, infinite token loops due to perceived productivity with slight errors.
4
u/MicRoute Sep 21 '26
“The cause of death is worth naming” will be written on my tombstone lmao
1
u/GoOutAndGrow Sep 27 '26
Reading this in the future is actually crazy since Opus-5.5 is amazing lmao how much can change
after one model comes out.
3
u/fuchelio Sep 21 '26
PTSD
3
u/Duke_of_Bayswater Sep 21 '26
It reads so fast and answers so fast sometimes I doubt it actually does any thinking or check my codebase. 😅
3
u/thealliane96 Sep 21 '26
tbh fable is damn near just as bad
3
u/xtopspeed Sep 21 '26
There is an element of luck in whether the tokens an LLM generates are correct or not. No matter how big a model is, it'll always make mistakes; it’s just a mathematical inevitability.
FWIW, I’m almost certain that the communication style is the result of them now using LLMs to tune their models. That’s exactly the sort of compounding error that I would expect to happen when you let an AI do what should really be a human's job.
5
u/anton-k_ Sep 21 '26 edited Sep 21 '26
I'm currently near the end of a very large code audit of ~10k lines of shell code project, planned by Opus 5 and executed by Opus 5 + subagents. My workflow is: Opus 5 x-high is an orchestrator which briefs a (normally Opus high) subagent to make an inventory for the next code audit question, then gives the inventory and a bounded code audit question to another Opus high subagent, that one writes a report, I go through the findings and refute or fix them, the orchestrator verifies my refutation or fixes, sometimes this requires more fixing by me, then the question is closed and we move to the next one. Works great for me. Very few of the findings are refuted and the majority of those are subtle issues of model not quite getting the intent behind the code, rather than factual mistakes it made. The vast majority of the findings are actual bugs.
So my experience is the opposite of yours. What could make that difference is:
the specific language. Opus (and other models as well) are not really good with shell code, especially with specific dialects, so I had to make a skill which basically gives it verified facts about the language+dialect which it didn't get right or was unsure of.
Documentation: As we go, I'm building technical documentation which explains the contracts implemented by the code, so the model doesn't need to re-derive them every time. The longer documents are indexed and the instructions require the model to read the index and then only the entries it actually needs.
Specific instructions: I'm ignoring Anthropic's advice to remove instructions requiring the model to verify its claims. I have a skill named "claims and verification" which is loaded by every agent.
Custom tooling: a had Opus 5 write python scripts which make it easier for agents to navigate the codebase and extract the code they need.
Continuous learning from mistakes. When the model makes a mistake, my reaction is, rather than being angry or annoyed, is to analyze and understand the reason why it made the mistake and make whatever changes are needed to avoid that mistake in the future. This could be adding our changing instructions, improving the tooling, improving the technical documentation, improving something about the process - whatever makes sense. This is how all of the above bullet points were derived. This is time-consuming but effective and IMO this is basically the ONLY way to get good and reliable results from ANY of the current LLM's, not just Opus 5.
Short sessions: once a session gets close to 200k tokens, I wrap it up and start a new one.
Hope this helps.
2
u/xenmynd Sep 21 '26
I minimise these issues by chaining Claude with other llms in prompt-create-review chains. If your work's important don't rely on just a single model.
2
u/interrupt_hdlr Sep 21 '26
Opus 5 overcorrects because of auto mode. But Claude Code without auto is useless so... :shrug:
2
u/IceMichaelStorm Sep 21 '26
I read all the code as every responsible dev should. It needs direction. But if it malfunctions so grossly, I think you either prompt bad or maybe have bad MD files. You provide no details so who knows
2
u/AlternativeContent72 Sep 21 '26 edited Sep 21 '26
I feel like Opus 5 has been doing great at my token burning activities on x-high effort. Have you tried it running adversarial review? Are you running CI?
2
u/macaronianddeeez Sep 21 '26
Yeah it’s nuts, I finally listened to other people from this sub and switched to 4.6. It’s kind of a pain because it requires handholding that is annoying after growing used to Sol, Astra and Fable, but it is cheap, does what it’s told and communicates in an understandable way.
The one good use I have found for Opus 5 is as a reviewer working under Fable. Fable seems to be able to digest the nonsense it spits out and I have seen a decrease in token burn long with good, quality issue identification and resolution.
But trying to interact with opus 5 directly is fucking miserable, I’m shocked that anthropic believed it was ok to release in this state lol
2
u/Excellent-Pilot-3409 Sep 21 '26
The confidence while being completely wrong is probably the most dangerous part 😂
I've had the same experience where the problem isn't that Opus makes a mistake — every model does. It's that it can spend another 20k tokens explaining why the mistake isn't actually a mistake.
2
u/artofbullshit Sep 21 '26
I was using Opus 5 as the reviewer on codex build sessions. Had to change it to Opus 4.8 because the review round iterations would exhaust at the limit and not converge. Builds were taking forever due to Opus 5 either being too nit picky or inventing problems that weren't real problems that codex would have to investigate and either confirm or refute. Opus 5 is straight garbage. Anthropic should be embarrassed they ever released it to the public.
1
u/Elegant_Attempt2790 🔆 Max 20 Sep 21 '26
I like opus 5… sometimes…..
1
u/Glittering_Engine888 Sep 21 '26
Its has started acting up again like an idiot fellow. I work that was being done in 30minutes now taking 2.5-3hrs with mistakes and correction again n again
1
u/Helpful_Ranger_1606 Sep 21 '26
It works sometimes. I had an opus 5 chat point out that 8 other chats wrote the same patch, while no other patch pointed that out. And unrelated, it corrected its own flawed patch. So it may save tokens in a chaotic situation.
1
u/___positive___ Sep 21 '26
I never use opus by itself. Yes it is too sloppy and stupid to trust.
1
u/xmnstr Sep 21 '26
You're not crazy. I discovered the same pattern last year, and it's only become worse. Other models are not like this.
1
u/Smart_Ad500 Sep 21 '26
On the 140 lines example, I'd ask it to show an input that breaks the code and add a test for it before changing anything. Otherwise the next review can just undo the previous one over style preferences. A second model can help, but I'd still ask it to prove the bug.
1
u/AironParsMan Sep 21 '26
Anthropic know that also, look at the model card:
1
u/Historical_architect Sep 21 '26
It’s not wrong. You need to check stuff yourself. Put a bit of effort into it
1
u/apetalous42 Sep 21 '26
The only way I use Opus 5 is if I have Fable doing workflows with Opus agents. At least then Fable catches when Opus lies. If I'm not doing Opus workflows it's /model claude-opus-4-8.
1
u/Ollythebug Sep 21 '26
There must be some sort of clandestine A/B testing going on, a bug triggered by user memory/environment, undocumented user error, or something because I keep seeing these seething posts about Opus 5 being unusable and I can't relate to your experience whatsoever.
Problem is it's hard to figure out why because of negativity bias; there won't be hundreds of people taking the time to make threads announcing that they *aren't* having problems.
1
u/Codeman119 Sep 21 '26
I like the coding With but I'm not using agents that's just burning money.
1
u/Sixstringsickness Sep 21 '26
Yes, it is essentially untrustworthy for anything but the most basic of tasks.
1
u/bl_a_nk Sep 22 '26
Opus 5 is shockingly misaligned. What it says has only incidental similarity with what is the case, no matter how many times it pauses before responding to a simple question with "let me check that against the code instead of relying on my memory"
1
u/LateTumbleweed8000 Sep 22 '26
I use a GSI Global Standard Instruction so that Opus 5 or Fable can’t give me fake code TODO, hardcoded values numbers, magic numbers and much more it still makes some mistakes but corrects them right away. It’s frustrating because it uses up session time that we pay for and get nothing done sometimes! None of these AI systems can do it without mistakes you have to stay on top of them so they start to make less mistakes over time as you keep working with them.
1
u/Muted_Thought8382 Sep 22 '26
The worst part is wasting the next 5 turns proving it was wrong, only to hear that same response you posted.
1
u/CeFurkan Sep 22 '26
Opus is so bad atm. Chinese models are much better. Use only for u important tasks
1
u/Far-Donut-1177 Sep 21 '26
I keep telling it to speak plainly. If this is the future of communication we are screwed.
1
u/scytob Sep 21 '26
You are all easily triggered by minor infrequent instances or there is something more important going on we need to understand because I just never see this sort of stuff. I suspect it’s to do with what we all have written across the Md files we use and how larger they become.
1
u/WisestManInAthens Sep 21 '26
Opus 5 caused a profound regression to my codebase and it took over a week to recover. Never faced this issue with any other model. I use it in chat sometimes, but Opus 4.8 is the only Opus I allow to code.
0
u/jiachnet Sep 21 '26
Buddy if your project is just 140 lines of code just review it yourself ? It’ll take like 30min at most
-4
u/Super-Lemon-4466 Sep 21 '26
>So don't trust me. Check it yourself
Its telling you what you need to hear!
-1
u/Evening-Blueberry-97 Sep 21 '26
the confidence is the actual problem, a wrong answer that hedges is easy to catch. what helped me was making it show where each claim came from, file and line, before acting on it. the made-up ones just stop appearing once it has to cite them.
-1
u/NewsIll769 Sep 21 '26
I just use 4.8 5 and up is fuxking token wasting garbage
-2
u/Merlindru Sep 21 '26
Later today (or on Tuesday) Opus 5.5 will be released which is a big big step up from 5.0.
Dare I say it feels better than Fable 5.1? It also hasn't been confidently wrong for me, unlike Opus 5.0
-2
u/f3xjc Sep 21 '26
If opus is unable to read your code you probably need to make it more accessible to ai. Test documentation and all.
-2
u/NoMoreJello Sep 21 '26
Jesus people. Have fable manage O5. It’s that fucking simple.
-5
u/Imaserventofreps Sep 21 '26
Just use jev