Is there anyway an action can be added to the API to allow notifications to be generated by e.g., gadgets? Or is this possible another way already?
Topic on Talk:Notifications
Feature request: API to add a notification?
I am afraid not.
I recall discussions on this issue, and the result has been to disallow procedural issueing of notifications to avoid mass misuse and bothering users and projects. Even more, there is no arbitrary message text permitted (which could be a hidden drug or weapon deal) communicated between two users, or offensive things which cannot be proved by the victim.
Therefore only standard situations like mentioning or thanking for an edit can trigger a notification, and the generated text is defined by the circumstances.