What is the recommended approach to limit a hidden application which is relevant only to a defined agent population taking part in a trial (a small subset of all agents)?

Enabling integration of web applications in the agent interface

Is there specific documentation you could point me to? 

Thank You

The interaction.web-content and workspace.web-content option can be defined on the annex of an Agent Group and will take precedence over what's defined at the application level. You can also define it on the annex of an agent, which will take precedence over Agent Group config.