Use OAuth 2.0 Token Exchange (RFC 8693) when an authorization server needs to accept an existing security token and issue a different one for an AI agent’s access. For delegation, keep the user and agent distinguishable: the user is the subject whose authority is represented, and the agent is the actor using that authority. Token exchange provides the protocol mechanism, not a complete agent-authorization policy or a way to obtain user consent.
What token exchange does—and what it does not do
RFC 8693, OAuth 2.0 Token Exchange, defines a token-endpoint extension grant for requesting one security token in exchange for another. It was published as an IETF Standards Track specification in January 2020. An OAuth client sends a token request to an authorization server; the server validates the supplied token information, applies its own policy, and decides whether to issue a new token.
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That makes token exchange a building block for an agent authorization design. It does not, by itself, establish that a user consented, define a universal agent identity, guarantee narrower permissions in the new token, or tell every resource server how to validate it. Those outcomes depend on the deployment’s authorization policy and token-validation arrangements.
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The key design choice is whether the system records the agent as a separate actor or treats it as the user. RFC 8693 calls these delegation and impersonation semantics.
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| Model | Identity meaning | Accountability implication |
|---|---|---|
| Delegation | The subject and actor are separate. The actor acts on behalf of the subject. | Actions can remain attributable to the agent while showing whose authority it represents. |
| Impersonation | The actor is treated as the subject within the authorized rights. | The resulting context may not preserve the same separate actor identity. |
For agent access where auditability matters, delegation is generally the semantics to design for. In a JWT, RFC 8693 defines the act claim to identify a delegated actor; it also permits nested actor relationships. An actor claim is identity information, not permission by itself. The authorization server still decides whether the agent may act for the subject and what the issued token permits.
How the exchange request represents the user and agent
RFC 8693 uses the required subject_token to represent the party on whose behalf the request is made. The request must identify its token type with subject_token_type. An actor_token can identify the acting party; if it is included, actor_token_type is required as well. The actor token is optional in the RFC, so deployments must decide whether and how their policy requires evidence of the agent identity.
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A simplified form-encoded request has this shape. The endpoint URL, token values, and token-type identifiers must be supplied according to the authorization server’s configuration and the token types it accepts:
grant_type=urn:ietf:params:oauth:grant-type:token-exchange
subject_token=SUBJECT_TOKEN_VALUE
subject_token_type=SUBJECT_TOKEN_TYPE
actor_token=ACTOR_TOKEN_VALUE
actor_token_type=ACTOR_TOKEN_TYPEThis is a schematic example, not a complete interoperable request: the values are deployment-specific, and an implementation must follow its authorization server’s supported parameters and policies. RFC 8693 also defines parameters for the requested token type and scope; a deployment may use resource targeting as appropriate. The RFC does not make scope or resource values universally meaningful—the server’s policy determines how they affect authorization.
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Design the flow from consent to resource access
Token exchange happens at the authorization server’s token endpoint. It does not prescribe the user-facing interaction that grants authority or obtains the initial subject token. Treat that work as a separate part of the system.
- Obtain user authorization. Choose an appropriate mechanism for the user-facing authorization step and acquire a subject token the authorization server can validate. The exchange specification does not prescribe this step.
- Establish the agent identity. Decide how the authorization server will recognize the agent and whether the exchange request must carry an actor token. If included, provide its token type too.
- Request an appropriately limited token. Send the exchange grant with the subject token and, for explicit actor representation, the actor token. Request the scope and resource or audience needed for the intended service, using the deployment’s defined conventions.
- Apply authorization policy at the server. Validate the presented tokens and decide whether this agent may act for this subject, which resources it may reach, and what authority the new token should carry. RFC 8693 leaves these decisions to the authorization server and deployment.
- Validate the issued token at the resource server. The receiving service must apply its configured token-validation and authorization checks before allowing the requested operation. Do not infer permission solely from the presence of an actor identity.
Decisions the deployment must make
Define the trust model
RFC 8693 does not prescribe one token syntax, trust relationship, or deployment policy for all systems. Specify which issuers and token types the authorization server accepts, how it validates them, and which systems are trusted to assert subject and actor identities. Align resource servers with the same trust and validation assumptions.
Limit authority deliberately
Decide how the server interprets requested scopes and resource targeting, and whether the issued token should carry less authority than the subject token. A request for narrower access is not proof that the server enforced attenuation; verify the policy and the resulting token behavior for the deployment.
Choose how actor identity travels
Decide whether the actor must be represented in the exchanged token and how downstream services will consume that information. RFC 8693 permits the authorization server to decide whether a resulting token contains composite subject and actor information. Systems that need consistent audit records should define how actor identity is preserved and checked across service boundaries.
Choose token binding and validation controls
Proof-of-possession and sender-constrained tokens are being explored in agent-oriented profiles, but they are not universal requirements imposed by RFC 8693. If a deployment adopts such controls, define which client or agent must prove possession, how the authorization server binds the token, and what the resource server verifies.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Published standard versus agent-profile drafts
The standards landscape is mixed: RFC 8693 is published, while the agent-focused documents below are Internet-Drafts—work in progress, not finalized standards. Their proposals should not be treated as guaranteed features of deployed authorization servers.
| Document | Status and date | What it proposes or contributes |
|---|---|---|
| RFC 8693, OAuth 2.0 Token Exchange | IETF Standards Track; January 2020 | General token exchange, including subject and optional actor token parameters and delegation or impersonation semantics. |
| Credential Delegation for AI Agents in Multi-System Environments | IETF WIMSE Internet-Draft; published July 28, 2026 | Proposes combining token exchange with proof-of-possession, Rich Authorization Requests, and OpenID Connect CIBA for scoped credential delegation across service providers. |
| OAuth Profile for Delegated AI Agent Authorization, version 02 | Informational Internet-Draft; dated August 30, 2026 | Proposes a profile using user authorization, resource-bound and sender-constrained JWT access tokens, token exchange for attenuated delegation, and refresh-token rotation. It says it does not standardize orchestration, policy languages, audit storage, or credential-vault APIs. |
| OAuth Actor Profile for Delegation | IETF Internet-Draft; published April 30, 2026 | Proposes a common actor structure and discovery metadata to address inconsistent actor representation. It leaves the decision to authorize an actor for a subject to deployment policy. |
IETF WIMSE interim presentation material also discusses OAuth, JWT access-token profiles, introspection, and token exchange as building blocks for agent authentication and authorization. It is discussion material, not a normative specification. The standards and drafts do not establish an empirical adoption or risk statistic for agent token exchange.
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How to assess an implementation
Before adopting an authorization server or agent integration, confirm its behavior against the design decisions that matter to your system:
Quick Recap
- Does it distinguish delegation from impersonation, and can the agent remain visible to downstream services?
- How does the user authorize access, and how is the subject token obtained before exchange?
- Can policy constrain the exchanged token to the intended scope and resource, and can you verify the resulting authority?
- Which token types and issuers are accepted, and how are subject and actor tokens validated?
- Does it support sender constraints or proof-of-possession if your design requires them, and which component enforces them?
- Which behaviors follow the published RFC, which are deployment-specific, and which depend on an evolving Internet-Draft?
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