Why AI Agents Should Never Hold Long-Lived API Keys

AI agents increasingly perform high-stakes tasks like moving money and updating records via APIs, but giving them long-lived API keys creates serious security risks. Unlike human users, agents act rapidly without supervision, can be manipulated through prompt injection, and often chain calls across multiple tools, amplifying the potential damage of a compromised credential. Security experts recommend replacing standing keys with short-lived, narrowly scoped credentials that specify the target API, permitted operations, affected resources, expiry time, and rate limits. A credential broker can sit between agents and secrets, resolving access at call time so the agent never directly handles sensitive keys, while also maintaining a full audit trail. This approach ensures that even if a credential leaks, it expires quickly and grants only minimal access, enforcing least-privilege security by default.