The completion and servicing of ultra-HPHT wells presents unprecedented challenges to operators. These challenges are primarily attributable to extremes in temperature, pressure, and depth. Today, there are a number of industry projects underway or planned in which downhole tools are required to operate over long periods of time at temperatures beyond 450 deg. F, hydrostatic pressures in excess of 20,000 psi, and depths greater than 25,000 ft. Ultra-HPHT tool requirements and offshore compliance requirements are driving the development of a new class of extremely high performance completion and service tools. Product reliability and longevity are challenges for these tools, as well as their conveyance, retrieval, and removal methods. Ultra-HPHT tools are usually developed on a well-by-well basis, and end-users are increasingly funding the development of these fit-for-purpose service and completion tools. Thus, the objective of this presentation is to explore these challenges and to discuss ways in which operators can effectively communicate their performance requirements to tool developers. By using a comprehensive, well-crafted set of requirements, the ultimate objective of achieving fit-for-purpose tools can be achieved.