Deutsche Telekom Nokia Telefonica Qualcomm Europe, Inc. Agentic AI systems rely on large language models to plan and execute multi-step tasks by interacting with tools and collaborating with other agents, creating new demands on Internet protocols for interoperability, scalability, and safe operation across administrative domains. This document defines a taxonomy for classifying Agentic AI use cases according to the functional protocol domains they exercise, such as transport, security and trust, discovery, identity, coordination and orchestration, data and context management, and operations and management. The taxonomy is intended to give the IETF a structured vocabulary for describing and comparing use cases, for identifying which protocol areas require standardization attention, and for mapping use case requirements to relevant IETF working groups.