Even before I type anything into Claude, I've already received the "instructions."
This is the system prompt. Although it is invisible to the user, it is a "background design document" that determines Claude's response style, values, and constraints. Anthropic has published the entire text in their official documentation. Opus from Haiku 3
Claude Opus 5 (Max) vs Claude Fable 5
Opus 5 to build a Kart racing game
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