I think it depends upon several items.
:Is he the contractor, or hired employee?
Contractor/owner= no tips
Employee= eligible
Did the employee go above and beyond what you expected of them?
If so then yes if he is permitted to by his employer, but should really be at a minimum such as cost for a drink or two or even lunch. It should be assumed he is being paid a wage which has been agreed upon between him and his employer as acceptable. So as not to give the impression of defrauding(the employer) or conflict of interest, tips should be minimal. IMO
If the employee did as expected and not above and beyond.
Then no tip should be given or expected. Services were rendered and given exactly as agreed upon.
