Every AI coding agent ships with baked-in behavior. Hidden system prompts you can't see. Tools you can't remove. Steering baked in by the company that made it.
It's just how these products work. Batteries included.
Claude Code has a system prompt. A long one. It tells the agent how to behave, what to prioritize, what to avoid. It's not exposed in the product. You can dig it out of the npm package if you know where to look, but you can't change it. Cursor has tool definitions and behavior rules that shape every interaction. Copilot has its own set of baked-in instructions.
And these prompts are good. They're written by smart people who understand the model. They make the agent useful out of the box.
But they're not yours.
