Give every AI agent a distinct, attributable identity, but do not mistake identity for permission. Authentication identifies or conveys a principal; authorization decides what that principal may do. Safe API access depends on narrowly granting authority, enforcing it wherever a resource can be reached, and recording which agent acted—and on whose behalf.
What does an agent’s identity prove—and what does it not?
An identity names the software actor making a request. It lets an API or resource evaluate policies for that actor and gives operators a way to attribute activity. It does not, by itself, define the actor’s permissions. Those come from authorization policy, token scopes or claims, and checks made by the service protecting the resource.
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A prompt that says “only read this file,” or an MCP tool allowlist that exposes only read operations, can help constrain behavior but is not a complete access-control boundary. If the agent has another route to the same resource—such as a shell that can run a cloud CLI—the resource’s own authorization must still deny operations the agent should not perform.
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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsAs AWS’s April 14, 2026 security guidance puts it: “You must assume an agent can do anything within its granted entitlements, whether OAuth scopes, API keys, or AWS Identity and Access Management (IAM) permissions, and design your controls accordingly.” Treat credentials and entitlements as the agent’s real capability, not as a guarantee that it will follow instructions.
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Which identity and authority model should an agent use?
First decide whether the agent acts as itself, acts with a person’s delegated authority, or connects to another system as a machine client. These are different authority paths; an implementation should make the selected path visible rather than quietly treating the agent as the user.
| Use case | Principal and authority | Implementation considerations |
|---|---|---|
| Agent acts as itself | The agent’s workload identity receives permissions for its assigned task. | Use a distinct identity per agent or workload where supported. Grant only the resource permissions the task needs, and log activity under that agent identity. |
| Agent acts for a person | The agent has its own identity and receives limited, user-approved delegated authority, commonly through an OAuth flow. | Preserve the represented user’s context without giving the agent the user’s raw credentials or silently granting the user’s full permission set. Make the delegation revocable. |
| Agent connects to a machine service | The agent authenticates as a client or workload, for example through two-legged OAuth or workload federation; a target may instead require an API key. | Restrict the client’s scopes and resource access. Obtain credentials through a managed mechanism rather than copying secrets into prompts or sharing them across agents. |
Agent acting as itself
Google Cloud describes Agent Identity as a cryptographically attested, SPIFFE-based identity for an individual agent, tied to its hosting resource. This is a Google Cloud implementation, not a universal property of agent identities. It is intended for cases where the agent acts on its own behalf, with access controlled separately through IAM and other applicable policies.
Agent acting with delegated user authority
Delegation should mean that a person has approved a defined access path—not that the model can borrow the person’s login. Google documents OAuth 2.0 three-legged delegation for agents acting for users. AWS guidance recommends passing signed user-context claims downstream rather than having an agent assume a role with the user’s entire permission set. This keeps the software actor and represented human distinguishable during authorization and investigation.
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Google’s MCP guidance warns of the practical attribution trade-off: when a client uses a person’s own identity, requests are attributed to that person and carry that person’s permissions. For production use, Google recommends a separate agent or workload identity so access can be limited and MCP activity can be attributed to the agent in logs.
Machine-to-machine access
For a system integration that does not represent a user, use a workload identity or client-credentials pattern appropriate to the platform. Google lists two-legged OAuth and OIDC federation among its options for external tools. Some target services still require an API key. Google marks HTTP Basic authentication as not recommended. Whichever method applies, the credential type does not replace resource-level authorization.
How do you bound permissions and prevent privilege escalation?
Start with a task-specific grant, then add controls that continue to constrain the agent if it tries an unanticipated action. An agent should not receive broad access merely because its future tool use is difficult to predict.
- Separate identities: assign distinct agent identities rather than sharing a static key or reusing a human role. Shared credentials blur attribution and make containment harder.
- Grant only needed access: limit permissions to the required APIs, actions, data, and resources. For MCP-connected resources, Google recommends minimum necessary permissions and describes using IAM attributes to prevent read-write MCP use on important resources.
- Use bounded, short-lived credentials: prefer workload identity, managed token or credential brokers, and expiring credentials over long-lived secrets embedded in agent context.
- Set hard limits: where available, use permission boundaries, policy conditions, explicit deny controls, and organizational guardrails. AWS identifies just-in-time elevation with automatic revocation as a maturity practice.
- Review access as the system changes: check for unused grants and permission drift. AWS cautions against expanding agent access reactively after an access-denied error and recommends reviews that account for changing tools and orchestration patterns.
- Provide a stop path: ensure delegated grants and credentials can be revoked when a user withdraws consent, an agent is compromised, or its task ends.
On Google Cloud, documented Agent Identity properties include no default sharing across workloads, no impersonation, and no developer-generated long-lived service-account keys. Google also says its cloud access tokens are cryptographically bound to unique X.509 certificates. These are platform-specific protections; do not assume an identity system elsewhere provides the same guarantees.
Where must authorization be enforced?
Enforce policy at each point that can grant access to the protected resource. A gateway or MCP server can control traffic that passes through it, but it cannot necessarily constrain an equivalent request made through a different tool or route.
Example: MCP restriction versus shell access
AWS’s 2026 guidance describes a managed-MCP condition that blocks a request through the MCP service but does not block the same agent from making an equivalent AWS CLI call through a bash tool. If both paths reach the same resource, an MCP-only rule is incomplete. Keep least privilege on the underlying IAM role and use applicable organizational controls, such as permission boundaries and service control policies, regardless of which route the agent takes.
Use gateways as an additional layer
Gateways can mediate tool and agent traffic, apply centralized policy, and improve visibility. Google’s May 6, 2026 announcement described Agent Gateway for agent-to-agent and agent-to-tool traffic. Gateway controls complement resource authorization; they do not eliminate the need to secure direct API access, command-line tools, or other alternate paths.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What should logs show, and how should credentials be handled?
Logs need to identify the acting agent and, where applicable, the human whose authority was delegated. Record enough context to investigate what resource was accessed, which authorization path applied, and whether the action succeeded. A log entry that attributes every delegated action only to the person—or only to a generic shared service identity—can obscure who actually initiated it.
Keep raw credentials out of prompts and model context. Google describes an Auth Manager that can manage API keys, OAuth client information, and delegated user tokens; an agent authenticates to it using its SPIFFE identity, and access events can be attributed to that identity. Managed credential systems and brokers can centralize acquisition, logging, and revocation, though the specific features depend on the platform.
What do current MCP and platform support claims mean?
MCP does not imply one universally available identity flow. Support depends on the client, server, transport, provider, and the authorization specification implemented. Google’s MCP authentication documentation says its Google and Google Cloud remote MCP servers implement the MCP authorization specification dated 2026-07-28 for HTTP transports. It also says those servers do not support Dynamic Client Registration or OAuth Client ID Metadata Documents. Depending on service requirements, a client may use an IAM principal or an API key.
That statement describes those Google remote servers and HTTP transports; it is not a compatibility promise for every MCP implementation. Confirm both ends of the connection support the intended authorization profile and registration flow before relying on it.
Product maturity is also time-sensitive. In its May 6, 2026 announcement, Google described Agent Identity for Agent Runtime and IAM allow/deny policies for Agent Identity as generally available. Agent Identity for Gemini Enterprise Agent Platform, Auth Manager, and several gateway and context features were described as preview; Principal Access Boundary was preview, and Unified Access Policy was described as coming soon. Those are release states as of the announcement, not guarantees of present availability.
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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →NIST NCCoE’s February 2026 concept paper frames agent identity and authorization as an active project covering identification, authorization, delegation, logging and transparency, and data-flow provenance. It identifies MCP, OAuth 2.0/2.1 and extensions, and OIDC as relevant practices under consideration. The paper describes project direction, not a final NIST standard or certification.
Quick Recap
Implementation checklist
- Name the principal: decide whether each request is made by the agent itself, under delegated user context, or as a machine client.
- Choose the authority source: document the workload permissions, approved delegation, client credentials, or target-required API key that authorizes the call.
- Limit and cap access: scope permissions to the task, use short-lived credentials where possible, and add conditions, boundaries, or explicit denies supported by the platform.
- Map every route: include MCP, direct API calls, shells, and other tools that could reach the same resources; enforce final authorization at the resource.
- Make actions attributable: log the agent identity and relevant user context, and confirm operators can investigate and revoke access.
- Verify compatibility and maturity: check the current provider documentation for the MCP transport, authorization profile, registration behavior, and feature release status you plan to use.
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