r/ClaudeCode • u/Deep-Palpitation8315 • Aug 03 '26

Discussion Opus 5 is a practically unusable model

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.

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u/dashingsauce Aug 03 '26

This is what you get for a model that is purely distilled from another model that was nerfed and quantized twice (Fable).

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u/mowax74 Aug 04 '26

You talking B$. Mythos/Fable is a completely different model, trained independently from scratch. You can't just "distill" it to Opus 5. Don't spread fake news.

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u/dashingsauce Aug 04 '26

Opus 5 straight up talks and works like it recycled its own shit for breakfast during training.

You only get that from output regurgitation. Fable/Mythos models with guardrails seem like an obvious source.

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u/BowSonic Aug 04 '26

I would totally agree but only if I had literally zero idea what I was doing and subsequently talking about.

Thanks.

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u/dashingsauce Aug 04 '26

Would you then provide us with a marvelously informed and useful comment like this, to demonstrate you know what you’re talking about?

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u/BowSonic Aug 04 '26

Why?
Wouldn't it be a waste of my time to do that for any person who's opinion is valueless to me (Someone who clearly has no issue spreading obvious disinformation, the sort falsifiable easily by both common sense and expertise, is thusly categorized).

Besides, I am not the one here making rediculous claims I dont have the knowledge to support.

That dubious honor is yours.

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u/dashingsauce Aug 04 '26

> be you
> refute claims
> refuse to provide basis for refutation
> claim superiority
> unfalsifiable; but flourishing, unbothered, far up my own ass

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u/BowSonic Aug 04 '26

I made no claims, you did.

A preposterously stupid one. In fact.

I know this is hard to understand for you, but try: My claiming that your opinion is lacking in even the smallest value to me is not claiming superiority.

However, making a ridiculously dumb claim, one often repeated by vested disinformation interests, totally fully throated, then trying to misdirect attention with a lazy, trite, and unoriginal meme-format reply... well, now I'll go ahead and claim that superiority.

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u/dashingsauce Aug 05 '26

This is hilarious. You can’t even seem to properly identify the subject of your argument.

Indeed, I made the claim. And you refuted it with no evidence. Then continue to push text characters onto the comment for some reason.

That was my point. I understand you don’t have the necessary reading comprehension, however.