China Telecom China Telecom Everything-OPS Futurewei Telefonica Exposure of network and service abstractions to external systems via YANG-based APIs has become an important means for operators to enhance their competitiveness. Despite the availability of numerous YANG data models, operators continue to face significant challenges in operationalizing these APIs in a consistent, scalable, and interoperable manner. Based on a typical use case, this document describes the problem space associated with operationalizing YANG- based service APIs, drawing on operator experience, IAB workshop findings to motivate requirements for improving API predictability and operational effectiveness through the upcoming ONIONS WG. In addition, it intends to gather operational needs and motivations for network and service abstractions to inform YANG data model refresh work.