This is a heavily interactive web application, and JavaScript is required. Simple HTML interfaces are possible, but that is not what this is.
Post
Simon Willison
simonwillison.net
did:plc:kft6lu4trxowqmter2b6vg6z
I put together an annotated version of the new Claude 4 system prompt, covering both the prompt Anthropic published and the missing, leaked sections that describe its various tools
It's basically the secret missing manual for Claude 4, it's fascinating!
https://simonwillison.net/2025/May/25/claude-4-system-prompt/
2025-05-25T13:51:06.347Z