/AI1h ago

Researcher Compares Fable 5 Outputs to Claude Models on Library Tasks

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Stella Biderman@BlancheMinerva#207inAI

Either I’ve already beaten the fallback mechanisms in Fable 5 or they don’t use Opus 4.8 / Sonnet 4.6 / Haiku 4.5 as the fallback. I’ve run several different tasks about upgrading our training library through each model and the output from Fable looks nothing like the others.

3:24 PM · Jun 9, 2026 · 532 Views
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Stella Biderman@BlancheMinerva

I haven’t read the Fable 5 output in detail because I’m on mobile and can’t test it right now, but even if it’s sandbagging it’s still much better than the other model options.

Stella Biderman@BlancheMinerva

Either I’ve already beaten the fallback mechanisms in Fable 5 or they don’t use Opus 4.8 / Sonnet 4.6 / Haiku 4.5 as the fallback. I’ve run several different tasks about upgrading our training library through each model and the output from Fable looks nothing like the others.

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Stella Biderman@BlancheMinerva

Unless it has introduced subtle bugs I guess? But it was much faster to identify the key changes necessary and provided the information in a better explained and clearer way. And the code looks better designed at a glance.

Stella Biderman@BlancheMinerva

I haven’t read the Fable 5 output in detail because I’m on mobile and can’t test it right now, but even if it’s sandbagging it’s still much better than the other model options.

1hViews 170Likes 2Bookmarks 0
Stella Biderman@BlancheMinerva

Demo with modifying our training library to add a recently developed parallelism technique:

Fable 5: https://claude.ai/share/17f83ad7-0e25-4d47-956c-ad5aa84a2af7

Opus 4.8: https://claude.ai/share/2302a275-be6f-4397-958d-53cb50f35c68

Stella Biderman@BlancheMinerva

Unless it has introduced subtle bugs I guess? But it was much faster to identify the key changes necessary and provided the information in a better explained and clearer way. And the code looks better designed at a glance.

1hViews 55Likes 0Bookmarks 0