wuweiaxin's short-lived-tokens-per-task is the right model, but it hits a ceiling: AWS IAM makes it native; most SaaS APIs don't. GitHub hands you a bearer token, Stripe too, Notion too. The proxy fills that gap. You get per-request scope enforcement without depending on the upstream service supporting fine-grained auth. That's the actual answer to paxys's question -- it's not about preventing the agent from making the same calls, it's about enforcing which calls it's allowed to make when the credential issuer won't.