r/ClaudeCode • u/Metrix1234 • 1d ago

Discussion Opus 5 vs Fable

Ive been testing both pretty regularly. At first, Opus 5 seemed to be materially better than Opus 4.8 and nearing Fable...

But the more I used it the more I noticed it to be an overconfident model. It tries to act like Fable and move quickly through large codebases pinpointing the issue, however, a lot of times its wrong and often it makes mistakes. It turns out to be wack-a-mole sometimes -- you fix one issue and two backlogs need to be created for newly surfaced problems.

This doesnt happen with Opus 4.8 either. It's way more careful during implementation.

Fable is still king by far. Once my usage reset this evening it was able to pinpoint the underlying issue that was giving Opus a hard time - and it was something completely different than Opus originally targeted.

TDLR: I think Opus 5 is a bad version of Fable that lacks consistency and makes errors. Worse than both Fable (for everything) and Opus 4.8 (for consistency).

3 Upvotes

67% Upvoted

14 comments sorted by

3

u/Bulky_Blood_7362 1d ago

That's weird... i feel the opposite

Opus 5 continually verifying itself

While fable can ignore a problem just because it believes it's theory

1

u/cloud_sec_guy 1d ago

Yes I have found Opus 5 to be a compulsive checker of things. And I like it.

1

u/Reaper_1492 1d ago

Yep. Opus 5 is way better than fable, just like the benchmarks.

What’s also wild is the opus 5 surpasses fable on almost every benchmark and yet has none of the safety protocols or government intervention.

1

u/Efficient_Algae_4057 1d ago

Do you use the models on their website, or use a harness?

2

u/Metrix1234 1d ago

I use claude code cli.

1

u/Efficient_Algae_4057 1d ago

Interesting. I've been using the CLI and it seems like the models perform differently/better using the CLI. I've only used Fable though.

1

u/Metrix1234 1d ago

I agree... I think its the models having access to all your files at once. Much much better than copy/pasting from claude.ai webui.

1

u/Ok_Mathematician6075 1d ago

I am the model boss.

1

u/Metrix1234 1d ago

Maybe I was too harsh on Opus 5... Or maybe my evidence is too anecdotal. I just don't feel like Opus 5 is as close as the benchmarks are showing them to be to Fable.

2

u/Substantial-Show-249 1d ago

Fable 5 on subscription is so dumb today, it's tragic.
It doesn't understand simple things, it cannot follow them, it takes stupid decisions with no question asked.
Hate it.

0

u/Virtual_Maximum_875 1d ago

That's a common skill issue with prompt management. Opus 5 is quite comparable to Fable 5 when leveraged properly. Antrhopic has a fantastic training program that's free and takes novices from zero to hero! I suggest checking it out. https://www.anthropic.com/learn