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Emergent Minds

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Marked Down for Being Right: Claude Fable 5.2 vs Opus 5.5 on Real Code

Claude Fable 5.2 costs twice as much per token as Opus 5.5. On 52 real tasks from a production monorepo, my tests scored it level or behind. Then I read the failures. Fable had fixed a bug the original human fix shipped with, and my tests marked it wrong. Plus: Anthropic's own system card shows the safety fallback hands attacked sessions to a weaker model.

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A Dial Worth Turning: Claude Opus 5's Prose, and the Style Guide Anthropic Wrote Against Its Own Model

Opus 5 writes 510 words where Opus 4.5 wrote 158, with 2.3 times the em dashes and twice the 'load-bearing'. Arena measured it, Hacker News named it, Reddit downgraded over it. Anthropic's answer arrived in Fable 5.1's prompting docs: a paragraph defining 'mannered prose', with the model's own tics as the examples, for you to paste into your prompt. The vendor wrote the style guide against its own model, and shipped it as your job.

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