Are your agents often performing other tasks that require their attention to be focused outside of Zendesk but you still want to be able to notify them of events occurring on a ticket?
Enabling chrome or firefox notifications for our notify app may be just the answer you are looking for.
To turn these notifications on, simply go to https://zendesk.sweethawk.co/ and click 'Allow' in the automatic popup like this:
(Note that this needs to be enabled individually for each agent that wants to receive them.)
Once you've allowed it, as long as there is an open tab with Zendesk–notifications that fire from that point on should also come through as Chrome or Firefox notifications (depending on your browser).