On-Behalf-Of (OBO) Tokens for Agents

Without OBO, an agent either calls APIs as itself, losing the user's authorization context, or carries the user's full access token, granting more authority than any single task requires. OBO solves both by exchanging the user's token for a narrower, time-bound token bound to the agent and the task. The pattern derives from OAuth 2.0 Token Exchange (RFC 8693) and is implemented across Microsoft Entra ID, cloud IAM stacks, and emerging agent identity platforms.

OBO tokens for agents typically provide:

• Subject and audience binding: The token records which user delegated and which downstream service may accept it.
• Scope narrowing: Each token carries only the permissions the agent needs for the current task.
• Short lifetime: Tokens expire quickly, limiting blast radius if leaked or reused.
• Delegation chain: The token preserves the user-to-agent-to-tool chain for audit and forensics.
• Per-call re-validation: Each downstream service re-checks the OBO token rather than caching authority.

Strong OBO discipline separates an agent that respects user authorization boundaries from one that quietly accumulates standing privilege. OBO tokens map directly to OWASP ASI03 mitigations on task-scoped permissions and to NIST 800-207 zero-trust principles for non-human identities acting in delegated contexts.

How PointGuard AI Helps

PointGuard's MCP Security Gateway brokers OBO tokens for every agent tool call, exchanging user credentials for narrow, time-bound tokens bound to specific agents, tools, and tasks. The Agent Governance Mesh then validates each OBO chain at runtime, preventing stale tokens or out-of-scope authority from reaching downstream APIs.

Learn More

RFC 8693: OAuth 2.0 Token Exchange

NIST SP 800-207 Zero Trust Architecture

OWASP Top 10 for Agentic Applications