You could add such tools to Draft Workbench which is entirely made in Python.
But you'd need to understand a bit how to access and manipulate topological shapes, and how to do mathematical transformations like rotations or changing placements. All Draft objects can be converted to Sketch objects using Draft_Draft2Sketch.
For example, see how the rectangle class is implemented. https://github.com/FreeCAD/FreeCAD/blob ... 4168-L4253
Also, there are two things, one is the internal rectangle class, and the other is the graphical rectangle tool, the latter meaning clicking on a button and dragging a mouse to create the rectangle. What you describe sounds like you would like to improve the graphical command, not the internal class.
The graphical command is a "GuiCommand" (Draft_Rectangle). https://github.com/FreeCAD/FreeCAD/blob ... 1020-L1138