Minimum agent API permissions can be incomparable rather than rankable

An agent needs the set of privileges sufficient for a proposed tool workflow, but a single scalar rank can obscure tradeoffs between different services, write scopes and administrator permissions. Two grants may each be minimally sufficient while exposing different resources. Selecting a broader grant because it is easier to rank loses least-privilege guarantees.

The paper examines 22,305 Microsoft Graph bindings and 23,852 Google API methods, reporting incomparable minimal grants on 29.8-33.3 percent of generated Graph tasks and 3.2 percent of Google tasks. The percentages refer to tasks generated from API tables and sampled decisions; they are not rates of actual excessive permissions in production customers or known exploited OAuth grants.

Use a partial-order comparison of permissions and evaluate alternative minimal grants against task-specific consequence dimensions before user consent. The case challenges one-number permission rankings, not the principle of least privilege itself. Primary evidence.

Additional evidence and trust boundary

The permission problem is a partial order, not necessarily a single ranked ladder. Where two minimum grants authorize different resources, both may be valid while exposing unequal write and administration surfaces. Consent should therefore show the set of sufficient alternatives and the concrete services, operations and administrative authority each permits. A scalar minimum can conceal this distinction. Supporting record.