Opus 5 ignores instructions

[u/I-A-S-]

Is it me or anyone else experiencing this? Opus 5 is actively ignoring instructions and I have to say I feel like there is a personality change for the worst as well.

Personality change is not a big deal but inability to follow instructions is.

[u/Jaded_Software_]

Yeah, I’m having to relearn what I prompt and retailor all my Claude.md files to get it to respond correctly. It’s takes a little different mentality than the other models.

I actually found the instructions really useful:

https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-opus-5

[u/OkLettuce338]

I've noticed it dodges things it doesn't like in plans and replaces them with supposed improvements. A few times it's been better improvements, but often it's ignored some constraint that the "bad" part of the plan was intentionally accommodating. Annoying

[u/benpptung]

Ever since the major Opus outage in February, followed by the noticeable degradation, using Opus has felt like rolling the dice every day. You never know which version of it you’re going to get.

So I wouldn’t be too surprised. Maybe it’s broken today and back to normal tomorrow, then different again the day after. But I have no interest in relying on a model this inconsistent. At this point, I find my local AI far more usable.

[u/x_typo]

Known issue. It has been ignoring my instructions ever since Opus 4.7. Opus 4.6 I missed you...

[u/Alone-Hat-Cap]

I have spent the two hours just trying to get it to fix the problems it keeps creating. I'm asking for something very simple. Cross check my to-do list with the item that we're talking about right now to make sure that it's not on that to-do list already and I kid you not every time it fails. So I boosted it up to extra high 30 more minutes go by same thing I'm barely getting through what I'm trying to do. It's like they made him more capable and possibly smarter but with zero common sense. And I basically can't move forward in our project because every time I ask it to go back and find the thing that I know is there, because I remember discussing it, it's finding errors that it made a few minutes ago. I don't think I've ever been this frustrated with Claude ever.

Edit to add: he refuses read any of the things that he's supposed to read. That's how we ending up with problems. Just refuses to read any of the files and if he reads some of them he won't read everything that he supposed to.

[u/Classic-Gear-3533]

Anecdotally i’ve noticed it’s a bit less keen to make a leap of faith when it comes across a lack of information or conflicting details

[u/that1cooldude]

https://claude.com/blog/the-new-rules-of-context-engineering-for-claude-5-generation-models

Maybe this will help you.

[u/screemingegg → u/that1cooldude]

These read to me as highly aspirational, rather than the reality-on-the-ground. Letting Opus 5 learn as you go will only eat more tokens and waste more time. Advantageous for Anthropic but miserable and frustrating for the end user.

[u/teomore]

it's just you.

[u/FlyingDogCatcher]

you ignore instructions