In the list of gmail api, the description for https://www.googleapis.com/auth/gmail.addons.current.action.compose is:
Manage drafts and send emails when you interact with the add-on.
However, I have not been able to use this scope to send emails.
In order to make it work, I am forced to upgrade to https://www.googleapis.com/auth/gmail.send.
My question is: what does "interact with the add-on" mean? Which limitations have to be in place in order for me to send emails just with https://www.googleapis.com/auth/gmail.addons.current.action.compose?
EDIT
I am building a google sheet add-on. The ideal manifest would include https://www.googleapis.com/auth/gmail.addons.current.action.compose, without resorting to https://www.googleapis.com/auth/gmail.send. This add-on would necessary include other scopes, but I'd like to keep the discussion general, without binding it to my specific setup.
https://www.googleapis.com/auth/gmail.addons.current.action.compose
As the scope name suggests, Google workspace addon can use that scope for sending email, only when in the compose user interface of the gmail and the user activates your addon. As written in the docs,
There are two ways to view an add-on's compose UI. The first way is to start composing a new draft or reply while the add-on is already open. The second way is to start the add-on while composing a draft.
Either case causes the add-on to execute the corresponding compose trigger function, defined in the add-on manifest. The compose trigger function builds the compose UI for that compose action, which Gmail then displays to the user.
Also see https://developers.google.com/workspace/add-ons/concepts/workspace-scopes#scopes.