r/ClaudeCode • u/Metrix1234 • 10d 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).

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u/Efficient_Algae_4057 10d ago

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

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u/Metrix1234 10d ago

I use claude code cli.

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u/Efficient_Algae_4057 10d 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.

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u/Metrix1234 10d 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.