Notification counter for 3rd party app

While the Amazon Connect agent workspace supports third-party applications, there isn't a specific feature mentioned for displaying a counter in the agent workspace tab for a third-party application. However, you might be able to achieve something similar by leveraging the contextual views feature for third-party apps.

The Amazon Connect agent workspace now supports contextual views for third-party applications, which allows the use of information from the current contact to automatically look up data or take certain actions in a third-party application. This feature is designed to help automate data entry and reduce mistakes.

For your voicemail application, you could potentially use this feature to display relevant information about new voicemails when a contact comes in. While it may not be a direct counter on the tab itself, you could design your application to prominently display the number of new voicemails within the application window when it's opened.

To implement this, you would need to develop your voicemail application as a third-party app for the Amazon Connect agent workspace. You can refer to the developer guide for instructions on how to build a third-party application and the admin guide for adding it to your contact center.

Keep in mind that the exact implementation would depend on your specific requirements and the capabilities of the Amazon Connect SDK. You may want to explore the full range of options available when developing your third-party application to find the best way to display the voicemail count to your agents.
Sources
Amazon Connect agent workspace supports contextual views for third-party apps (preview)
Working with third-party applications in the Amazon Connect Agent Workspace - Agent Workspace