Retrieval is enough when the job is answer generation. You need an agentic workflow when the system must decide, route, call tools, enforce approvals, and complete work across systems.
RAG is usually enough when
The user mainly needs grounded answers
There are no meaningful system side effects
The workflow ends with a recommendation, not an action
Agentic workflows are needed when
The system must route, draft, update, or execute
Approvals and action controls matter
Performance depends on multi-step decisions across tools