arXiv:2610.40981v1 Announce Type: new Abstract: General-purpose AI agents require authority that changes between tasks and during execution. Common deployments trade broad permissions that expose unnecessary authority and narrow permissions that raise approval requests. Existing mechanisms can enforce dynamic authority, but agent tool interfaces rarely provide the agent's planner, the component that chooses its actions, a means of comparing the authority required by alternative actions or of seeing the cost of the authority it already holds. Drawing on the rich history of access control research, we propose the concept of \emph{elastic least privilege}, in which an agent begins with a small baseline of authority and may acquire more within an owner-defined envelope. Elevations are leased and measured against a replenishing budget. Their cost increases with power, proximity to mandatory safety invariants, and repeated requests. Costs are visible to the planner, which can prefer lower-privilege choices and release authority it no longer needs. Authority returns automatically to the baseline when a lease expires, when it is released, or when the budget is exhausted, while persistent legitimate demand may prompt an owner-approved change to the baseline. Building on prior risk-priced and budget-aware access control, we redesign these mechanisms for agents. How best to implement the approach and how well it works in practice are open research questions. In this paper, we present how the approach could work, illustrate the model, and set an open research agenda.