Least Privilege

The security principle that an identity — human or agent — should hold only the access it needs for its task, and no more. For AI agents it's the single highest-leverage control, because agents chain tools: the blast radius of a compromised agent is the *union* of every scope it can reach, so every unnecessary permission compounds. Least privilege is exactly what shadow agents skip — they typically borrow a human's full OAuth grant (an agent that needs to draft replies in one label inherits the entire mailbox, drive, and calendar). Enforcing it means giving each agent its own scoped Non-Human Identity (NHI) with narrow, short-lived, revocable permissions rather than a broad standing token. Pairs with approval gates for irreversible actions and sandboxing for code execution.