An assistant needs the right information for the job. Its context window is the limited working space available for a response, measured in tokens. Depending on the model, that budget includes instructions, supplied material, conversation, tool results and generated output.

You can improve the brief: purpose, audience, constraints and relevant evidence. That is one useful control, alongside tool choice, permissions and how you check the result. You may not see or control all the context the product adds.

Imagine a folder on a colleague’s desk. A useful folder contains the material needed for the task, with versions and instructions clear. A larger pile is not automatically a better brief.