@nomeyer –– welcome to the GitHub Support Community! Thanks for asking about this here.
It’s possible to mention a person or team on GitHub, but not a GitHub App at this time.
However, one approach that you can take is configuring the application to subscribe to a specific events and take action from there based on its contents.
For example, you could configure the application to request the
read and write permission on
issues and subscribe to the the issue_comment event. Once a new issue comment is created, edited, or deleted, your application will receive a webhook payload and you could have your application parse the content and create a new issue comment) as a response.
While some may prefer to develop in other frameworks and languages, it may be worth mentioning Probot, a framework for building GitHub Apps in Node.js here. Probot’s community has numerous featured applications that you could leverage for your own project, including a
probot/commands extension that adds slash commands to GitHub which might be interesting to you and your team.
Given that context, we’re always working to improve GitHub and the GitHub Support Community, and we consider every suggestion we receive. If you want to see native support for mentioning GitHub Apps, would you mind submitting this through our official product feedback form so that our product team can track your request? That’s the best place to share requests like these in consideration for future iterations of GitHub. Thank you!