Adding tooltip to an operator button

Hi, do you know how can I add a tooltip to an operator button?

I have a dictionary with keys id, name, description.
This dictionary structure is placed in a list to compose the buttons.

for i in guiList:
            op = col.operator("myoperator", text=i["name"])

The code works fine, obviously the text parameter exists, but is there any parameter for tooltips?
What I would like to do additionally is to offer some tooltips when the user hovers above the button.

Tooltip texts can’t be given dynamically. The bl_description property of a class is taken as tooltip and can’t be overriden.

EnumProperty() supports descriptions for every item however.

All right, I converted the code to use operator_enum instead of a for loop and now it’s all good.

6 years later, and this is now a feature of blender 2.81.

From the docs:

With an operator defined as (irrelevant parts omitted):

class WM_OT_tooltip_test(bpy.types.Operator):
    arg: bpy.props.StringProperty()

    def description(cls, context, properties):
        return "Arg is: " + properties.arg

The following button would have a tooltip that says “Arg is: FOO”.

layout.operator('wm.tooltip_test').arg = 'FOO'

This is mainly intended for cases when multiple similar but distinct operations are implemented for technical reasons as one operator with a mode switch parameter.