Building with LLMs
Context Engineering
10 min+100 XPStep 1/11
The window is the whole game
At inference time, the model knows nothing except what's in the context window — every instruction, document, tool definition, and message has to physically be there. Context engineering is deciding what earns that space.
Prompt engineering is one slice of it. The full job: system instructions, retrieved knowledge, tool schemas, conversation history, memory, and the user's message — all competing for a fixed budget.
analogy
Prompt engineering writes the question. Context engineering builds the entire desk it lands on — the files, the rules, the tools within reach.