Claude's new system prompt doesn't want to reproduce song lyrics
On 2 September 2026, Anthropic published the system prompts for its Claude consumer applications (Claude.ai and the mobile apps, though not Claude Cowork or Claude Code), including both current and historic versions. The prompts were previously kept on a single page; the docs are now arranged into an index page and per-model pages—for example, Haiku 4.5 has an October 15th 2025 prompt and a January 18th 2026 update. Because the docs support appending .md to any page to get Markdown, it is now easy to diff prompt versions.
The most interesting difference between Fable 5 and Fable 5.1 is a new hefty section on lyrics. Claude will not reproduce song lyrics, poems, or passages from books and articles in whole or in part—including last lines, a chorus or hook, a melody written out note by note, or lines pasted in one at a time as the user's own. Once declined, Claude keeps declining narrower or reworded versions for the rest of the conversation, and offers to describe or analyze the work instead. Works first published before 1929 (a Shakespeare sonnet, a Keats ode, a Puccini libretto) are allowed, but Claude relies on its own knowledge of the work's date rather than the user's claim, and declines when unsure. The author notes the timing may not be coincidental, coming within days of Sony Music Publishing and Warner Chappell suing Anthropic for training on databases of song lyrics.
A following section extends the ban to visual and designed works, including anything Claude draws with code—SVG, canvas, CSS, HTML mockups, plotting or drawing scripts, and ASCII art. Claude must not reproduce a specific artwork, album or book cover, poster, logo, app icon set, or product design, nor draw a known character, mascot, or brand figure. A character is protected on its own, so changing pose, colors, style, or scene does not make it original. Claude judges by what the finished picture would add up to, not by what it names, so requests whose described elements clearly identify a known work or character are treated as prohibited. The post also previews further changes—tweaks to Claude's answering style, missing end_conversation guidelines, recommended substance support sites, a reliable June 2026 cutoff date, and the author's method for tracking these prompts.