Glossary › Context Engineering
Context Engineering
The discipline of designing everything the model sees on a given turn: system prompt, tool definitions, retrieved documents, memory, and prior turns, under a fixed token budget. Succeeded "prompt engineering" as the senior skill once tool lists and retrieval made the prompt the smaller part of the context.
Where Context Engineering shows up
All matching postsContext Engineering: Designing What the Model Sees
The context window is a budget, and everything competes for it: the system prompt, the tool list, retrieved documents, memory, and the conversation so far. Learn to design the context deliberately, scope tools per task, compact without losing what matters, and treat cache hit rate as the metric it has become.
Context and Harness Engineering
Two disciplines that decide whether an agent works: designing what the model sees (context engineering) and building the runtime that validates what it does (harness engineering). Learn the context budget, per-task tool scoping, memory write policies, and a minimal harness with permissions, budgets, verification, and traces.
Context Engineering vs Prompt Engineering: What Changed
Prompt engineering optimized the instruction. Context engineering optimizes everything the model sees: tools, retrieval, memory, history, and tool results, under a token budget. Here is why the discipline changed names, what it optimizes for now, and a before-and-after on a real agent.