Let say I'm creating an issue in Jira and write the summary and the description. Is it possible to call a python script after these are written that sets the value for another field, depending on the values of the summary and the description?

I know how to create an issue and change fields from a python script using the jira-python module. But I have not find a solution for using a python script while editing/creating the issue manually in Jira. Does anyone have an idea of how I manage that?