The model reasons over whatever is on the board, and nothing else. That single fact is the foundation for everything practical about using these tools. Shape the window well, with the right instructions, the right documents, the key constraint kept in view, and you get sharp answers. Let it fill with noise, or let what mattered slide off the edge, and the good stuff gets drowned out.

The next chapter is about the most direct way you write onto that board: the prompt. We will see why the exact words you choose change the answer you get, and why that is not a quirk to work around but a direct result of the next-token machine you met last module.