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Version: v0.1

Introduction

Buyer agent and dealership digital storefront connected by typed AAP messages

Auto Agent Protocol (AAP) is a strict A2A v1.0 profile that defines the typed automotive data shapes AI agents and car dealerships exchange when they discover, browse, and submit leads.

AAP does not invent a new wire protocol. It rides on top of the A2A (Agent2Agent) specification: every AAP message travels inside an A2A Message.parts[].data value as a typed DataPart. Dealers MAY expose their AAP skills via either A2A binding — JSON-RPC 2.0 or HTTP+JSON/REST. gRPC is out of scope for v0.1.

The extension is identified by a single URI:

https://autoagentprotocol.org/extensions/a2a-automotive-retail/v0.1

A dealer agent declares itself AAP-compliant by listing this URI in capabilities.extensions[] of its A2A agent card and by implementing one or more of the five standard AAP automotive skills. Agents pick the subset they support; AAP RECOMMENDS at least inventory.search + lead.submit for an end-to-end shopping flow, but neither is mandatory.

What AAP standardizes​

Honeycomb of five AAP skills: dealer.information, inventory.facets, inventory.search, inventory.vehicle, lead.submit

AAP v0.1 defines a vocabulary of five standard skill IDs that cover the read-and-lead lifecycle of automotive retail. A dealer agent picks whichever subset matches its capabilities — none of the five is individually mandatory.

SkillPurpose
dealer.informationDealership profile, locations, brands, hours, contact channels, capabilities
inventory.facetsAggregated counts and ranges over the dealer's inventory
inventory.searchFiltered, paginated inventory queries
inventory.vehicleDetail view of one specific vehicle (by VIN, stock, or vehicle_id)
lead.submitUnified consented lead carrying customer info plus optional vehicle of interest, trade-in, and appointment

It does NOT cover authentication beyond bearer, payments, financing approval, RFQ/quote workflows, trade-in valuations, or reservations. Future versions MAY extend this surface; v0.1 is intentionally minimal.

Layered architecture​

Three-layer stack: HTTP at the bottom, A2A v1.0 in the middle, AAP automotive profile on top

AAP sits as a profile on top of A2A, which itself sits on top of HTTP. AAP never touches the wire format directly — it defines the shape of typed DataParts that A2A bindings carry.

Anything an A2A client already does — message envelopes, task model, error mapping, server-sent events — works unchanged. AAP only specifies the typed payloads inside DataPart.data.

Quick start​

A buyer agent talks to a compliant dealer agent in three steps.

1. Discover the agent​

Fetch the A2A agent card at the dealer's well-known URL:

curl https://demo-toyota.example.com/.well-known/agent-card.json

Confirm the card lists the AAP extension URI under capabilities.extensions[].uri and exposes at least one supported_interfaces[] entry whose protocol_binding is JSONRPC or HTTP+JSON.

2. Pick a binding​

A2A defines two protocol bindings AAP supports. Both carry identical AAP payloads.

BindingA2A specAAP page
JSON-RPC 2.0A2A Section 9JSON-RPC binding
HTTP+JSONA2A Section 11REST binding

3. Send a typed AAP message​

Wrap an AAP request inside an A2A Message and POST it to the agent endpoint. Below is the simplest call — dealer.information over the HTTP+JSON binding (using the A2A v1.0 wire format):

curl -X POST https://demo-toyota.example.com/a2a/message:send \
  -H "Content-Type: application/json" \
  -d '{
    "message": {
      "messageId": "01HZ9G5N8D1Y4M6SP9C4XKVW3Q",
      "role": "ROLE_USER",
      "parts": [
        {
          "data": { "type": "dealer.information.request" },
          "mediaType": "application/vnd.autoagent.dealer-information-request+json"
        }
      ]
    },
    "configuration": {
      "acceptedOutputModes": ["application/vnd.autoagent.dealer-information-response+json"]
    }
  }'

The dealer agent replies with an A2A Message whose first DataPart.data is an AAP response:

{
  "message": {
    "messageId": "01HZ9G5P2KA8RT9WMS3B4C5D6E",
    "role": "ROLE_AGENT",
    "parts": [
      {
        "data": {
          "type": "dealer.information.response",
          "data": {
            "dealer_id": "dealer_demo_toyota",
            "legal_name": "Demo Toyota of San Francisco, LLC",
            "trade_name": "Demo Toyota",
            "brands": ["Toyota"],
            "address": {
              "address_line_1": "100 Market St",
              "city": "San Francisco",
              "state": "CA",
              "zip": "94105"
            }
          }
        },
        "mediaType": "application/vnd.autoagent.dealer-information-response+json"
      }
    ]
  }
}