Claude's new system prompt really doesn't want to reproduce song lyrics

Claude’s new system prompt really doesn’t want to reproduce song lyrics

2nd September 2026

Anthropic publish the system prompts for their Claude consumer applications (Claude.ai and the Claude mobile apps—sadly not for Claude Cowork or Claude Code). I love that they do this, and that they share not just the current prompts but historic changes to their prompts as well.

They used to keep all of the prompts on a single page, but when I checked today I noticed they had re-arranged those prompts into an index page and then a page per model—here’s the page for Haiku 4.5 for example, which has the original prompt from October 15th 2025 and an updated prompt from January 18th 2026.