Hello Shilpa,
Out-of-box a Classification solution to predict the assignment group uses a Before Insert Business Rule to trigger the prediction. So, if the short description changes before the record is inserted, it will make the prediction on the text in the short description that was changed.
Applications such as Predictive Intelligence for Incident Management will provide out-of-box Predictive Intelligence solutions and business rules to implement these features. For more flexibility with classification solutions, consider using ITSM Predictive Intelligence Workbench, which provides prebuilt use case templates and guides you through your machine learning implementation to create intelligent ITSM business processes.
Hope this helps.
Regards,
Brian
