Agreement is written with the assumption that Owner will execute a version of the WSBA. Cost plus fixed fee consultant agreements.A design consultant agreement is a contract that defines the working relationship between an independent design consultant and their client. § 3.1 The Consultant will be required to provide Type of Service to include but not limited to the following: Fill out services required. 535, Standard Form of General. Conditions of Contract Between Owner and Design-Builder (2022 Edition), and requires.