The best first use case is usually a task you already understand. Familiarity makes it easier to notice when the agent produces something plausible but wrong.
Look for a visible artifact
Release-note drafts, dependency-review notes, and proposed patches have outputs you can inspect. Define what a complete artifact contains before running the use case. Avoid a goal so broad that any output can be called progress.
Bound the tools
Give access to the minimum workspace needed for the task. A release-note draft can begin from a fixed set of commits and issue descriptions. It does not need publishing credentials to demonstrate whether the writing is useful.
Specify failure behavior
Missing inputs should produce a clear explanation. Conflicting instructions should produce a question for the reviewer. A failing check should produce a report, not repeated attempts to bypass the check.
Compare against your current process
Keep the same input and review criteria for a manual run and an agent-assisted run. Record the time spent reviewing as well as the time spent producing the artifact. The purpose is to learn where the use case helps and where it creates extra work.
Expand one boundary at a time
Once the task is repeatable, change one permission or one input at a time. Preserve the review step until you have evidence that the new boundary is appropriate. These are illustrative evaluation suggestions, not benchmark results.