AI agent or deterministic workflow? A decision guide

Choose a deterministic workflow when the steps and decision rules are known in advance. Consider an AI agent when the task requires interpreting variable information or choosing among uncertain next steps. Many useful systems combine both: model-based interpretation inside a predictable process with explicit controls.

Start with the variation in the task

Imagine two invoice requests. In the first, a structured form contains a customer ID, approved amount and fixed template. Conventional automation can validate fields and prepare the document. In the second, an employee forwards a messy conversation and asks what still needs clarification. Language understanding may help identify gaps, but the final amount should still come from an authoritative record.

The presence of text does not mean the whole process needs to become autonomous. Limit model judgment to the part where it adds value.

Compare the operating tradeoffs

• Fixed rules are easier to inspect when inputs are predictable.
• Model judgment can handle varied language but needs evaluation.
• A workflow may be simpler to recover when each stage is explicit.
• An agent may explore several paths, increasing cost and uncertainty.
• Both need correct permissions and evidence of completion.

For a hybrid design, draw a box around the judgment step. Specify the input, allowed output and what happens when confidence is insufficient. Do not let a free-form model response silently become an executable instruction.

Run a small comparison

Take a representative set of past tasks that you are authorized to reuse, or create synthetic equivalents. Try the fixed-rule path first. Record the cases it cannot handle. Add AI only for those variations, then measure the extra review effort as well as the successful outputs.

If the agent adds reasoning but saves no useful work, simplify. If fixed rules repeatedly misroute legitimate requests, a constrained classification or extraction step may be enough.

Write down the choice

A good decision record names the variable part of the task, the reason AI is needed and the fallback when it cannot decide. This makes later maintenance easier than a broad statement that the business is now agent-powered.

Be Human editorial guidance. Examples are illustrative unless explicitly attributed. Sources provide background; implementation choices depend on your workflow.