Arena Analysis: Opus 5.5 Cuts Em Dashes 95% and Reads Less Like AI, but Answers 6% Longer
rohanpaul_ai · x · 2026-09-27
- Arena analyzed Claude Opus 5.5's writing against Opus 5 on high-reasoning Text Arena outputs: 10 of 12 writing measures improved.
- Fewer AI tells: em dashes fell from 15.2 to 0.8 per 1,000 words (a 95% drop) and semicolons fell 73%; long content words dropped from 41.7% to 38.6%, the lowest of any Claude model analyzed.
- More readable but longer: average sentence length fell 17% (12.14 to 10.03 words), yet answers grew 6% wordier (453 to 481 words), the longest in the Opus family.
- A new tell may be emerging: increased hedging and caveats.
Related event: Text Arena: Opus 5.5 Writes More Like Humans, Em Dash Use Down 95%(5 posts)→
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