When you create a report from a standard report in Report Libary, a description of the report is included that is visible by hovering over the "i" next to the name. This feature is not available when creating a custom report. Every report should have a description of what question the report is designed to answer. This feature is already included when creating a custom Property. It is essential that the same functionality is available for information about a report. Look at some of the descriptions already in standard reports to come up with a character limit if necessary, but documentation should be a prime objective in a CRM.