Protocol and Adoption Reality

Google's Agent2Agent protocol, A2A, standardizes communication between agents rather than between an agent and its tools. As publicly described, an agent publishes an agent card that advertises its capabilities and endpoint, other agents discover it, and they exchange tasks and messages over a defined protocol so that an agent built by one team or vendor can delegate to and collaborate with an agent built by another. It addresses a genuine and growing problem: as organizations field many agents from many sources, those agents need a common way to find each other and hand work back and forth, and without a standard every pairing is a custom integration. A2A, introduced with broad industry backing, is a credible answer to inter-agent communication, complementary to tool-access protocols rather than overlapping them.

The Structural Choice: An Agent Is an Endpoint That Advertises Capabilities

A2A models an agent as a service: a discoverable endpoint with a capability card and a messaging interface. The protocol defines how agents announce themselves, how tasks are framed and exchanged, and how results return, which is exactly what inter-agent communication requires. What it deliberately does not define is the internal constitution of the agent behind the endpoint. The agent card describes what an agent can do, not what an agent is made of: there is no standardized, portable representation of the agent's intent, memory, governing policy, proposed mutation, or lineage as a structured object that could move between systems intact. A2A standardizes the conversation between agents while leaving each agent an opaque service whose internal state is its own implementation's concern.

What the Agent Schema Provides

The agent schema standardizes the thing behind the endpoint. A semantic agent object is a structured entity carrying six canonical typed fields, intent, context, memory, policy reference, mutation descriptor, and lineage, so the agent is a portable, serializable, governable object rather than an opaque service. Inter-agent collaboration over A2A gains from this directly: when the agents that discover and delegate to each other are semantic agent objects, a delegation can carry the governing policy and the lineage of the work, the receiving agent can validate the structure of what it is asked to do, and the trail of which agent did what under what authority is recorded rather than lost at the endpoint boundary. A2A defines how agents talk; the schema defines what each agent is as it talks, and the combination makes multi-agent collaboration governable rather than merely connected.

Composable, Not Competing

A2A and the agent schema sit at different layers: a communication protocol between agents, and a structural definition of the agent. Agents represented as semantic agent objects can discover and delegate to one another over A2A, so the two are additive. The schema supplies the portable, governed object that A2A's messaging moves between, turning a network of opaque services into a network of governable objects. No relationship, endorsement, or infringement is asserted; the comparison is architectural.

Disclosure Scope

The semantic agent object and its six canonical typed fields, with structural validation, partial-agent support, and traceable semantic lineage that make the agent a portable, governable object, are disclosed in the agent schema filing (U.S. Application No. 19/452,651). This article compares that disclosed object model with Google's publicly documented Agent2Agent protocol and positions the schema as the agent-object layer beneath A2A's inter-agent communication. References to A2A are to its public specification and are used for comparison only.