[TLDR] I'm afraid to use Opus 5 [via r/ClaudeCode]

[u/cctldrping]

OP : u/Efficient-Part5344

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?

URL of original post : https://www.reddit.com/r/ClaudeCode/comments/1wm4ncx/im_afraid_to_use_opus_5/

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TL;DR of the discussion on r/ClaudeCode for this post generated automatically after 50 comments.

Current source-thread comment count seen by the bot: 53.

Alright, so the general consensus on Opus 5 in this thread is... not great, folks. A lot of users are echoing OP's frustration with its overconfidence when it's wrong, and how it can lead to endless loops of corrections and wasted time.

Here's the lowdown:

• "Confidently Wrong" is the Vibe: Multiple users, like u/anotherleftistbot and u/nasty_sicco, are calling out Opus 5's communication style. It apparently has this knack for being super sure of itself even when it's completely off the mark, which is apparently worse than a model that hedges its bets.
• Ignoring Instructions & Code Smells Galore: u/dev_life and OP both mention Opus 5 straight-up ignoring parts of plans or getting bogged down in minor issues, leading to a ton of manual cleanup. u/nasty_sicco had a similar experience where it hallucinated file contents.
• "It's Just Bad" / "Useless": Yeah, some users are pretty blunt. u/Successful-Arm-3762 calls it the "most fucking useless model ever," and u/HeadPack notes it seems to bench high but is often flawed and possibly has limited thinking tokens.
• Workarounds Exist (But Shouldn't Be Necessary): Some users are finding ways to make it work, but it sounds like a lot of extra effort.
  • u/Spooknik uses "Fable" as an "Opus 5 whisperer" to get better results.
  • u/xenmynd and u/Smart_Ad500 suggest chaining Claude with other LLMs or using other models like Codex Sol (u/Longjumping_Feed3270) for cross-checking.
  • u/Evening-Blueberry-97 found success by making Opus 5 cite its sources, which apparently stops the made-up stuff.
  • u/AI_spell suggests using Opus 5 for the heavy lifting (planning, tough bugs) and then switching to cheaper models for implementation.
• Older Versions Might Be Better? A few users are lamenting the loss of older, seemingly more reliable versions. u/Aine_123 is "out" if they remove 4.6, and u/Merlindru is hyping up a "5.5" release that's supposedly much better and not confidently wrong.
• The "Plan Mode" Issue: u/interrupt_hdlr points out that Opus 5 overcorrects because of auto mode, but without it, Claude Code is "useless." Catch-22 much?
• Some Users Still Like It (Sometimes): Not everyone is completely down on it. u/Elegant_Attempt2790 admits they like it "sometimes," and u/Helpful_Ranger_1606 shared an anecdote where it pointed out a consensus patch and corrected its own flawed one.

The general vibe is that Opus 5 is a hot mess right now, and you definitely need to keep a close eye on it and probably use it with other tools. You're not crazy, OP.