I will allow to specify a max width (in characters) for (at least) the name of the flows like I did for the name of the use cases.
To show the input/output parameters just draw the activity in the diagram moving it by drag&drop and choose "draw activity" (rather than "add a call behavior"), the activity's parameters will be automatically drawn. Example (from screenshots
Let's note I recommend to draw first
the activity in the diagram and to probably increase its size, because all its sub elements must be drawn inside
the rectangle representing the activity.
P.S. you speak about developers
, since the beginning I am working alone on Bouml