Specify what “finished” looks like
Try “Read the shared picnic checklist and identify items with no owner. Show me the gaps before changing the list.” When the answer arrives, compare it with the checklist. If somebody already volunteered in a private conversation, ask them before assigning their name. A useful output might be three unassigned items with a source record for each. A list of general planning tips would not satisfy that request, even if the advice sounds sensible.
Write a task brief
Use four lines: outcome, allowed sources, allowed changes and stopping point. For the picnic example, name the shared checklist, ask for a gap report, allow no edits, and stop when every item has either a recorded owner or an explicit blank. Use permissions that actually prevent writes if you require a read-only trial.
Check the result yourself
Pick one claimed gap and open the original record. Did a person accept the task, or did another person merely suggest them? Correct any ambiguous wording before sending a request. A household assistant can identify missing evidence; it should not fill that gap by inventing a volunteer.