The Letting Centre

Our tenant has become an agent for a utility company and proposes to run this business part time from our property.  He has a full-time shift job outside of the house.  I naturally do not want the address of the house used in any form of advertising and he has told me that he has been allocated a free phone number so that the tel number of the house is not advertised either.  I wish to make an amendment to his tenancy agreement to allow him to do this but state clearly that it remains a residential agreement and that on no account should the address/tel number be advertised.  What is the best way to do this? 
Thanks for reading
Charente