Claude Opus 5.5 Writes 17% Shorter Sentences

Arena.ai compared Claude Opus 5.5 and Opus 5 answers across 12 writing metrics. Sentence length fell 17% (12.14 to 10.03 words), em dashes dropped 95% (15.2 to 0.8 per 1,000 words) and semicolons 73%, while answers grew 6% longer and hedges like "perhaps" rose 97%.

• Em dashes: 15.2 → 0.8 per 1,000 words, down 95%
• Average sentence: 12.14 → 10.03 words, down 17%
• Average answer grew 6%, from 453 to 481 words
• Hedges like "perhaps" and "arguably" rose 97%