A summary is required for the Item Description for any geographic information system (GIS) service that is being shared with ArcGIS Online. Currently, your service does not have a summary. If you plan on sharing this service with ArcGIS Online at a later date, add a summary to the Item Description.
Solution
Fill in the summary on the Item Description tab on the Service Editor dialog box before publishing the service.
More information
When serving content, it's important to provide a summary of your service so that consumers of the service will know who created the service, its origination, and when and how it was created. The summary can be added by accessing the Item Description tab on the Service Editor dialog box and populating the appropriate field.
The Service Editor dialog box can be accessed from the main menu in ArcMap by clicking File > Share as > Service.