How to Add Google Workspace Add-on to Gmail Message Toolbar on Hover

[shayandev91]

Hi everyone,

I'm trying to add a Google Workspace Add-on to the Gmail message toolbar that appears when hovering over an email in the inbox message list (not when viewing the full email). I want the add-on icon to be available in that quick-action toolbar, similar to how icons like "Snooze" or "Archive" appear on hover.

I've already developed and published the add-on, and it shows correctly in the side panel when viewing a message. However, I can't find documentation or a setting allowing the add-on to appear in the hover-over toolbar directly in the inbox.

Is this currently supported? If so, how can I configure my manifest or add-on behavior to enable this?

Thanks in advance for any guidance or documentation links!