Points to consider
The advertisement should make it clear what the business need is so that suppliers can see what services are required and the organisational structure and skills and resources needed to deliver these. Suppliers can then assess whether they can do it/want to do it. Where following Restricted, Negotiated Procedure or Competitive Dialogue, you may need to issue a PQQ to candidates who have expressed an interest.
Ensure that the questions are permitted for selection of bidders (see: Introduction to the EC procurement rules) and support your evaluation criteria.