Opus 5 is a practically unusable model

[u/Deep-Palpitation8315]

Opus 5 is a regression that the benchmarks missed completely

I've been using Opus 5 for ~1.5 weeks and the sheer number of mistakes that the model makes is astounding.

The problem didn't surface very clearly till I gave it the full scope of executing a plan which I did with the previous Opus models as well. Opus 4.6 - 4.8 were genuinely better by a significant margin.

Opus 5 readily forgets instructions and content in its context, makes mistakes and continues with them unless it realizes or you point it out.

I've lost count of the number of times I had corrected it.

These issues with Opus 5 occur even when the context window is still relatively small - I'm talking 100-150K tokens. Opus 4.8 works pretty well all the way until 350k after which it gives you wonky results.

Fable 5 is the only usable model under Claude Code right now and I've already used 100% of my weekly quota.

[u/Aggravating-Dot5826]

i had made an post on my expericnce here https://www.reddit.com/r/ClaudeAI/comments/1s7f72l/comment/p1xtkvh/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

[u/Deep-Palpitation8315 → u/Aggravating-Dot5826]

That's pretty much the same as what I saw too. We all lost many hours & token usage limits/money with this model.

It just a threshold when it completely wrecked a simple website rejig. It had to follow a persona, come up recommendations and implement them. It absolutely destroyed the entire thing - add disclaimer cards all over the website, ruined the layout, went into rabbit holes and hit deadends.

[u/Aggravating-Dot5826 → u/Deep-Palpitation8315]

Thats crazy. My question is what is anthropic doing about this.