Define required fields on closing of post or ticket

I would like the ability to define required custom fields on closing of a post or ticket. Right now I can set a field as required but what typically happens is that the needed details for the field are not yet known to the agent so they put in bogus details to get around the requirement. In other systems I have had the ability to define a required field on closing. This helps to allow the agent to get to work on the client request and once all the details are known the agent can properly answer the questions to ensure all the correct data is captured when marking a ticket or post with a closed status.