Hi Riccardo,
At first sight I thought "but of course, why didn't I think of that".
But on second thought, the whole purpose of running the Project Tool is because I need to add a new plugin to the solution.
So, I actually don't need to update a single plugin project, but need to update the solution project ... well, I mean, the project containing the solution.
As far as I have understood I would these need to run the Project Tool on /plugins/ which will thus update all plugins' projects.