I cannot add any description to the customer interaction history through the sugar CRM app for Android Devices. Is there any way this can be done or can this action just be done by the browser?
It sounds like your Mobile Detail vs EditView layouts are different.
Go to Studio -> Opportunities -> Layouts -> Mobile Layouts, and ensure that the Description field is on the "EditView" layout. Save and Deploy, then visit the Opportunity on your mobile app, and as Dmytro said above, use the three vertical dots in upper right corner, and select "Edit".