What a system prompt does, and which of Anthropic's are published

What it shows

A base unit with a cartridge slot above a separate input tray; the green cartridge stands for the system prompt, given apart from the user's message.

Its labels

• New: A role in the system prompt shapes Claude's behaviour and tone
• The user's message goes in separately
• Claude Code's own system prompt is not published

The story

What a system prompt does, and which of Anthropic's prompts are published · 3 Nov 2026