Least privilege scopes what an agent may do, one tool call at a time. But a perfectly authorized agent can still be compromised by what it is allowed to see. Least exposure is the broader control: task-scoped minimal disclosure for prompt context, retrieved documents, tool schemas, secrets, business rules, approval context, memory, and downstream responses. Because the model is untrusted reasoning, every input is attack surface. A Mission should therefore bound both halves: the actions the agent may take and the working set it may reason over.
Identity Assertion Trust Framework and Domain-Authorized Issuer Trust Method
Self-service agent sign-up exposes a first-contact trust problem: a Resource Authorization Server can verify a perfectly valid JWT and still not know whether the issuer is allowed to assert identities for the user’s domain. That is two questions, not one. Federation proves the issuer is authentic, but not that the namespace owner authorized it, and static allowlists do not scale to onboarding unknown domains at runtime. The Identity Assertion Trust Framework lets a Resource AS publish the evidence it requires. The Domain-Authorized Issuer Trust Method lets a domain owner publish which issuers may assert identities in its namespace, fail-closed, the way mail and the web already pushed authority into DNS. Both compose with ID-JAG and the JWT-bearer grant without changing the grant surface.