import bpy

class addObjectPrimitives(bpy.types.Panel):
    bl_label = "Add Object"
    bl_space_type = "VIEW_3D"
    bl_region_type = "TOOLS"
    bl_context = "objectmode"

    def draw(self, context):
        layout = self.layout
        col = layout.column(align=True)
        col.operator('mesh.primitive_plane_add', text = "blah")

bpy.utils.register_class(addObjectPrimitives)