Pattern
Escalation Path
When the agent is uncertain or out of its competence range, it escalates to a human or to a different agent — explicitly.
When to use
Always. Every agent system needs at least one escalation path: "if confidence < X, stop and surface to human." Without it, the agent fabricates with high confidence in cases it should have refused.
When not to use
When the system is read-only and low-stakes. Even then, "no answer" is usually a better fallback than "hallucinated answer."