An API exposes capability, not just data
A network service may offer interfaces for reading status, provisioning capacity, or changing configuration. These operations have different consequences and should not inherit one broad permission. Define supported callers, resources, actions, and operating limits. Encryption protects a channel but does not decide whether a request is authorized. Begin with the capability being exposed and the operational harm an unintended change could cause, not merely the convenience of integrating the endpoint into another application.
Enforce access at the receiving service
Validate identity and permission for the actual target and action. NIST’s resource-focused zero-trust principles are relevant because a caller should not gain broad authority from its network location. Do not assume an upstream interface has already made every necessary decision. Separate read access from writes and administration. Test cross-tenant and cross-resource requests as part of authorized evaluation. A legitimate account or a successful connection is not proof that every submitted operation is permitted.
Constrain automated callers deliberately
AI agents and orchestration tools can generate requests that look plausible while exceeding the task they were assigned. OWASP recommends explicit authorization for sensitive tools and independent validation outside model reasoning. Define allowable operations, meaningful limits, and approval requirements where appropriate. Bound retries and duplicate changes according to the application. A service should not accept a consequential action simply because a caller includes a statement that someone approved it or because a generated explanation sounds convincing.
Maintain useful evidence and support ownership
Record outcomes and relevant configuration without exposing credentials or unnecessary payloads. Identify who investigates rejected requests, unexpected changes, and integration failures. CISA’s buyer guidance highlights the value of audit capabilities and secure product practices. Preserve tests across API revisions so a supplier update does not silently broaden access. Future network programmability creates opportunities only when interfaces remain bounded and accountable; adding more endpoints without clear permissions can make operational risk harder, not easier, to manage.