Claude system prompt update targets song lyric reproduction

Simon Willison posted notes comparing the Fable 5.1 system prompt to Fable 5. The changes focus on preventing reproduction of song lyrics. Anthropic publishes the system prompts for its Claude consumer applications including Claude.ai and the mobile apps. The company does not publish prompts for Claude Cowork or Claude Code. Willison stated that he appreciates the publication of these prompts.