Context engineering means giving the AI exactly the information it needs for a task, no more and no less.
Example
Instead of a whole manual, you give the assistant only the relevant chapter, your rules and one good example.
For pros
It extends prompt engineering to everything that lands in the context window: system instruction, tool descriptions, retrieved documents, conversation history and notes. Too much or irrelevant context measurably worsens answers, so agents trim their history and fetch knowledge only when needed.
