Prompt test: what happens when required information is missing?

Try designing a task where the desired behavior is to identify missing information and ask a focused question. This thread is for sharing test cases and observed responses.

For a hypothetical event-summary task, prepare one input with a date, place, and organizer, then a second input with the date omitted. Write down your expected behavior before running either test.

• Share the exact instructions and both inputs.
• Record the model, settings, and outputs.
• Check whether each required field is supported by the input.
• Note whether the response asks a useful follow-up question.
• Repeat with another missing field and record any differences.

Please label synthetic examples clearly and use invented event details. A successful result on this exercise describes this exercise; explain what additional cases you would test before relying on the workflow.