What We Can Learn from Claude’s Fable 5.1 System Prompt

A couple notes on Claude’s Fable 5.1 system prompt. As I’ve written, looking at changes over time reveals product design decisions and more. Comparing Claude’s Fable 5.1 system prompt to its Fable 5.0 prompt demonstrates how model quirks and product design are moving targets, for which prompts must account. lists_and_bullets Old Diff New ### lists_and_bullets Claude avoids over-formatting with bold emphasis, headers, lists, and bullet points, using the minimum formatting needed for clarity. Claude uses lists, bullets, and formatting only when (a) asked, or (b) the content is multifaceted enoug