ANTHROPIC SAYS IT FIXED CLAUDE'S WRITING. I RAN THE EVALS TO CHECK

Summary from the TLDR Data newsletter

Anthropic's writing changes in Opus 5.5 appear to work partly: em dashes fell by 99.6% and other recognizable “Claudisms” fell about 50% versus Opus 5. The bigger lesson is methodological: style evals work better when you annotate exact problematic spans and judge recurring rhetorical moves, not just banned phrases or vague overall scores.