We analyzed tens of thousands of real-world, high-reasoning Claude Opus and Fable outputs from versions 4.5 to 5 in the Text Arena and found that @claudeai's writing has changed in more ways than one: Across language complexity, patterns and markers, we now see: Claude’s answers have become much longer: - Opus 5 averages 510 words per response - This makes Opus 5 responses 3x longer than Opus 4.5’s average of 158 Responses have also become more structurally elaborate from Opus 4.5 to Opus 5: - 58% rise in average sentence length - 46% rise in clause frequency rises However, the vocabulary itself is not becoming more difficult, making Opus 5 longer and more structurally complex, but lexically simpler between 4.5 and 5: - 6.8% pt drop in long content words (46.9% to 40.1%) - 53% drop in abstract nouns (6.02 → 3.79 per 1k words) Writing habits people notice are much more common in Opus 5: - 2.3x as many em dashes - ~2x as many phrases like “load-bearing” - 50% more honesty wording like “honestly” and “frankly” Fable 5 is 38% more concise than Opus 5, averaging 316 words vs. 510. At the same time, it is nearly 2x as likely to include praise/validation or open with phrases like “yes, exactly”