Who participates: the Context Engineer
The Context Engineer is the architect of the Agents, Rules, and Skills system. Not a prompt engineer. Not a technical writer. Their job unfolds across three dimensions that correspond exactly to the tripod:
| Work dimension | What they design | Key decisions | Critical skill |
|---|---|---|---|
| Agent design | Which Agents exist, what role each plays, how they interact, what limits they have. | How many Agents do I need? Where are the boundaries between roles? | Thinking in teams and responsibilities. |
| Rules design | Global norms: conventions, constraints, standards. What is non-negotiable. | What applies to all Agents and all Skills without exception? | Normative precision without ambiguity. |
| Skills design | Decomposes the solution into self-contained work units. Calibrates the detail level of each one. | What does each Agent need to know to complete each Skill without asking questions? | Decomposition without information loss. |
The Context Engineer works on all three levels simultaneously. When designing an Agent, they think about which Rules govern it and which Skills it will execute. When defining a Rule, they think about which Agents apply it and which Skills it affects. When creating a Skill, they think about which Agent will execute it and which Rules constrain its action space. The three elements are designed together, never separately.
The composition shift
The composition of the group changes significantly from Phase 2. In Solution Phase, the key was breadth — including every stakeholder who could block the solution. In Context Phase, the key is depth. The Context Engineer is the central role, supported by technical stakeholders who can validate architectural decisions and by the product team that ensures fidelity to the Problem Statement and Solution Brief.
The stakeholders from Phases 1 and 2 don't disappear — they become the validators. When the system produces outputs, these stakeholders are the ones who judge whether the context is working: "Is this a faithful expression of what we defined?"
The best Context Engineer is not who knows the most about AI. It's who best understands what the AI doesn't know. Each Rule answers: "What could go wrong if I don't say this?" Each Skill answers: "What does a completely ignorant Agent need to know about the world?" Each Agent answers: "What role do I need and what must that role NOT do?"