Use the simplest thing that works
If you can draw the steps as a fixed flowchart, build a workflow. Reach for an agent only when the steps depend on what it finds.
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Analogy
Don't add Redux to a page with one checkbox. Don't add an agent to "extract invoice, save to DB".
In an agent
Saying this in an interview signals you've shipped real systems, not just demos.
Practice
Flashcards
- Interview: agent or workflow, which do you default to?A workflow: cheaper and predictable. Use an agent when the path depends on what is found.
Interview questions
- Agent vs workflow?
- A workflow runs steps you designed in advance, in a fixed order.
- An agent lets the model choose the next step in a loop, until the goal is met.
- Workflows are cheaper, faster and easier to test; agents handle open-ended tasks.
- Default to a workflow; use an agent when the path depends on what is found.
Questions people ask
How do I know if my task even needs an agent?
Try to draw it as a flowchart. If every step and branch can be drawn in advance, build a workflow, or even a single model call. Reach for an agent only when the steps depend on what it discovers along the way, such as investigating why a deploy failed.
Why do interviewers like the simplest thing that works answer?
It shows you have shipped real systems. Agents add cost, latency and failure modes, so choosing them by default is a warning sign. Saying you start with the simplest design, and add an agent only where the path is unknown, tells the interviewer you weigh trade-offs instead of following hype.