If you want to specify which agents have access to Zingtree from within their Zendesk view, you would enable Role Restrictions in this way:

1. In Zendesk, as the administrator of your account, open the Zendesk Admin portal.
2. Click Manage, My Apps, and select the Agent Scripting app.
3. Click Change Settings. The image below shows your current view.
   
4. For Role Restrictions, check the Enabled box.
5. Select which agent roles you would like enabled.

Please note that Zendesk offers Role Restrictions only for the Enterprise Platform.