Use brush in vertex paint mode with python


I want to use brush in vertex paint mode.

I choose the brush according to:
bpy.ops.paint.vertex_paint(stroke=[], mode=‘NORMAL’)

and I get the following errors:

RuntimeError: Operator bpy.ops.paint.vertex_paint.poll() failed, context is incorrect

It seems that python wants to get the mouse location.
However, I want to do it manually, i.e to give the location of vertex, view, radius and paint the mesh.
How can I add it in order to do it automatically?