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

Simon Willison · published 2 September 2026

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2blogs citing
First cited
2 Sept 2026
Most recent
4 Sept 2026
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38
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Blog
In the post
Date
modelcontextexperience.com
It's worth understanding Anthropic's watermarking a bit better Read at the source ↗
4 Sept 2026
sippey.com
Claude's new system prompt Read at the source ↗
2 Sept 2026

Links from this post

Link
Host
https://platform.claude.com/docs/en/release-notes/system-prompts/overview
platform.claude.com
https://claude.ai/
claude.ai
https://platform.claude.com/docs/en/release-notes/system-prompts/claude-haiku-4-5
platform.claude.com
https://platform.claude.com/docs/
platform.claude.com
https://platform.claude.com/docs/en/release-notes/system-prompts/overview.md
platform.claude.com
https://platform.claude.com/docs/en/release-notes/system-prompts/claude-fable-5-1.md
platform.claude.com
https://github.com/simonw/claude-system-prompts/commit/837a418b5888207b1b11b27d2f5471970da6f99b
github.com
https://www.theguardian.com/business/2026/aug/31/aanthropic-sued-alleged-theft-songs-ai-train-claude
theguardian.com
Claude Fable 5.1 made me a really nice animated pelican Read at the source ↗
simonwillison.net
https://claude.ai/share/3e5a199c-27f2-4c51-b66b-2c6f808ed500
claude.ai
https://claude.ai/share/f78010eb-8d52-4f73-aff9-775e333f8180
claude.ai
https://dancesafe.org/
dancesafe.org
https://tripsit.me/
tripsit.me
https://psychonautwiki.org/
psychonautwiki.org
https://platform.claude.com/docs/en/models/fable-5-1/overview
platform.claude.com
https://simonwillison.net/2026/Apr/18/extract-system-prompts/
simonwillison.net
https://github.com/simonw/claude-system-prompts
github.com
https://github.com/simonw/claude-system-prompts/commits/main/prompts/claude-fable.md
github.com
https://github.com/simonw/claude-system-prompts/commits/main/prompts/claude-opus.md
github.com
https://github.com/simonw/claude-system-prompts/commits/main/prompts/claude-sonnet.md
github.com
https://github.com/simonw/claude-system-prompts/commits/main/prompts/claude-haiku.md
github.com
https://github.com/simonw/claude-system-prompts/commits/main/prompts/claude-opus-4.md
github.com
https://github.com/simonw/claude-system-prompts/blob/main/prompts/claude-opus-4.md
github.com
https://github.com/simonw/claude-system-prompts/commit/defcf92d14e064bb17abddc308e2aa58446d5eb5
github.com
https://github.com/simonw/claude-system-prompts/blob/main/CHANGELOG.md
github.com
https://simonw.github.io/claude-system-prompts/feed.atom
simonw.github.io
https://github.com/simonw/claude-system-prompts/blob/8b5c87dbd70103a037ae5777b8d9365571cf9562/summarize_commits.py
github.com
https://github.com/simonw/claude-system-prompts/blob/main/.github/workflows/update.yml
github.com
https://github.com/simonw/claude-code-transcripts
github.com
https://gisthost.github.io/?f1399e27b6a832f0e790b696af812c9b/index.html
gisthost.github.io
https://simonwillison.net/tags/ai
simonwillison.net
https://simonwillison.net/tags/git-scraping
simonwillison.net
https://simonwillison.net/tags/prompt-engineering
simonwillison.net
https://simonwillison.net/tags/generative-ai
simonwillison.net
https://simonwillison.net/tags/llms
simonwillison.net
https://simonwillison.net/tags/claude
simonwillison.net
https://simonwillison.net/tags/ai-ethics
simonwillison.net
https://simonwillison.net/tags/system-prompts
simonwillison.net