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Authorize agent-to-agent communication with Cerbos

Control which agents can communicate, what capabilities they can share, and what data flows between them with policy-driven authorization powered by Cerbos.

Authorization for AI Talk to an engineer Agent skill for writing authZ policies

Inter-agent authorization

Control which agents can communicate and what capabilities they can share through fine-grained Cerbos policies

Task delegation control

Authorize task delegation between agents based on user identity, agent roles, and task type at runtime

Audit every interaction

Every agent-to-agent authorization decision is logged with full context, giving you a complete audit trail of multi-agent workflows

How Cerbos works with Agent2Agent Protocol

AI agents and tools introduce a new class of authorization challenges. They act on behalf of users, access sensitive data, and chain operations, all of which need fine-grained access control.

Cerbos provides policy-driven authorization that controls what AI systems can do, which data they can access, and on whose behalf. Policies are written in human-readable YAML and evaluated at request time.

With Cerbos and Agent2Agent Protocol, you get guardrails that scale with your AI adoption, centrally managed policies, full audit trails, and sub-millisecond decision times that don't slow down agent workflows.

Policy-as-code Human-readable YAML policies managed like source code Scalable PDP Stateless policy decision point with sub-millisecond latency Centralized management Manage, test, and deploy policies from a single control plane

How Cerbos authorizes Agent2Agent interactions

1. Define policies for agent communication, Write YAML policies that specify which agents can communicate with each other and what task types can be delegated, based on user identity and context.
2. Source agent requests authorization, Before sending a task to a remote agent via A2A, the source agent sends the user context, target agent, and task type to the Cerbos PDP.
3. Cerbos evaluates the inter-agent request, The PDP applies fine-grained rules considering the requesting user, source agent capabilities, target agent, and the nature of the delegated task.
4. Task proceeds or is blocked, Cerbos returns an allow or deny decision. The orchestration layer enforces it, with every decision logged for audit.

Security risks of unsecured agent-to-agent communication

Without authorization at every inter-agent interaction, multi-agent systems introduce risks that traditional application security doesn't cover:

• Privilege escalation through delegation. An agent can delegate tasks to another agent with broader capabilities, silently expanding the effective permissions beyond what the originating user is authorized for.
• Incomplete identity context. As tasks pass between agents, the delegating user's identity is often reduced to a bare ID. Without the full profile, downstream agents can't enforce fine-grained restrictions.
• No audit trail. Without authorization checks at each delegation step, there's no record of which agent invoked which, on whose behalf, or why it was allowed.
• Transitive trust. Multi-hop delegation chains can compound permissions — agent A delegates to B, which delegates to C — with no single point verifying the end-to-end authorization.

Richer multi-agent decisions with Cerbos Synapse

Agent-to-agent communication often carries only partial identity context. Cerbos Synapse enriches each inter-agent authorization request with the delegating user's full profile from your identity provider, resource metadata from your data stores, and each agent's constraints — so the PDP receives complete context for every delegation decision.

FAQ

How does Cerbos authorize Agent2Agent interactions?

When one agent sends a task to another via the A2A protocol, Cerbos evaluates policies to determine whether the requesting agent (on behalf of a user) is authorized to invoke that remote agent's capabilities. Each inter-agent interaction is individually authorized.

How is this different from the MCP integration?

MCP governs tool access within a single agent's context. A2A governs communication between agents. Cerbos can enforce both — controlling what tools an agent can use (MCP) and which other agents it can delegate to (A2A).

Can I control which agents communicate with each other?

Yes. Cerbos policies can restrict agent-to-agent communication based on the requesting user's identity, the source agent, the target agent, and the type of task being delegated. Policies are written in YAML and managed outside your application code.