Study Finds 13,000 New AI Writing Tells

Graphite analyzed AI-generated text and identified about 13,000 words and phrases that signal machine authorship. The top tell is "this matters," appearing 116 times more often than in human samples, especially in Claude Opus 5.5. While Opus 5.5 is shedding its tells over time, OpenAI's Astra is trending toward less human-like writing.

• Graphite identified about 13,000 words and phrases as AI tells
• "This matters" appears 116 times more often in AI text than human
• Claude Opus 5.5 uses em dashes 99% less than Opus 5
• OpenAI's Astra uses "does not establish" 275 times more than Claude