Discovery

Every AAP-compliant dealer agent publishes an A2A v1.0 agent card at the well-known URL on its own domain:

GET https://{dealer-domain}/.well-known/agent-card.json

The card MUST declare the AAP extension and list the AAP skills the agent implements (one or more from the v0.1 vocabulary of five). The buyer agent uses the card to confirm AAP compliance, discover which skills are actually available, select a protocol binding, and (if auth_type is bearer) negotiate credentials before calling any skill.

Required AAP additions to the A2A agent card

A2A leaves discovery flexible; AAP narrows it. An AAP-compliant agent card MUST satisfy all of:

1. capabilities.extensions[] contains an entry whose uri equals:

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

2. That extension entry SHOULD set params.manifest_url to the absolute URL of the agent's contract manifest (/.well-known/auto-agent-contract.json).

3. That extension entry SHOULD set params.aap_skill_ids to the AAP v0.1 vocabulary, and params.implemented_skills to the subset this agent actually supports:

   {
     "aap_skill_ids": [
       "dealer.information",
       "inventory.facets",
       "inventory.search",
       "inventory.vehicle",
       "lead.submit"
     ],
     "implemented_skills": [
       "inventory.search",
       "lead.submit"
     ]
   }

4. skills[] contains one entry per AAP skill the agent implements (one or more). Buyer agents discover capability from skills[], not from the AAP extension URI alone. AAP RECOMMENDS that an agent expose at least inventory.search + lead.submit for a meaningful shopping experience, but no single skill is individually required.

5. supported_interfaces[] lists at least one entry whose protocol_binding is JSONRPC or HTTP+JSON.

A buyer agent that does not find a matching extension URI MUST treat the agent as a generic A2A agent, not as an AAP dealer agent.

Authentication declaration

Two modes are supported in v0.1:

security_requirements	security_schemes.bearer	Meaning
absent or empty	absent	Public agent. Anyone may call the agent over the listed bindings.
present and references bearer	present	Bearer token required. Clients MUST send Authorization: Bearer <token> with every call.

The contract manifest's auth_type field MUST agree with this declaration: null for public, "bearer" for bearer. See Contract manifest.

Full example agent card

This is a complete, valid AAP v0.1 agent card for a public dealer agent that exposes both bindings.

{
  "name": "Demo Toyota Dealer Agent",
  "description": "Dealer agent for Demo Toyota of San Francisco. Implements the Auto Agent Protocol v0.1 (A2A Automotive Retail Profile).",
  "version": "1.0.0",
  "provider": {
    "organization": "Demo Toyota of San Francisco, LLC",
    "url": "https://demo-toyota.example.com"
  },
  "documentation_url": "https://autoagentprotocol.org/docs/v0.1/intro",
  "supported_interfaces": [
    {
      "url": "https://demo-toyota.example.com/a2a/jsonrpc",
      "protocol_binding": "JSONRPC",
      "protocol_version": "1.0"
    },
    {
      "url": "https://demo-toyota.example.com/a2a",
      "protocol_binding": "HTTP+JSON",
      "protocol_version": "1.0"
    }
  ],
  "capabilities": {
    "streaming": false,
    "push_notifications": false,
    "extended_agent_card": false,
    "extensions": [
      {
        "uri": "https://autoagentprotocol.org/extensions/a2a-automotive-retail/v0.1",
        "description": "Auto Agent Protocol v0.1 — A2A Automotive Retail Profile.",
        "required": true,
        "params": {
          "manifest_url": "https://demo-toyota.example.com/.well-known/auto-agent-contract.json",
          "aap_skill_ids": [
            "dealer.information",
            "inventory.facets",
            "inventory.search",
            "inventory.vehicle",
            "lead.submit"
          ],
          "implemented_skills": [
            "dealer.information",
            "inventory.facets",
            "inventory.search",
            "inventory.vehicle",
            "lead.submit"
          ]
        }
      }
    ]
  },
  "default_input_modes": ["application/json"],
  "default_output_modes": ["application/json"],
  "skills": [
    {
      "id": "dealer.information",
      "name": "Dealer Information",
      "description": "Return dealership profile, locations, brands, business hours, contact policies, and supported services.",
      "tags": ["dealer", "profile"],
      "input_modes": ["application/json"],
      "output_modes": ["application/json"]
    },
    {
      "id": "inventory.facets",
      "name": "Inventory Facets",
      "description": "Return aggregated facets (makes, models, years, conditions, price/mileage ranges) over the dealer's inventory.",
      "tags": ["inventory", "facets"]
    },
    {
      "id": "inventory.search",
      "name": "Inventory Search",
      "description": "Search vehicle inventory by make, model, trim, year, condition, price, mileage, and other filters.",
      "tags": ["inventory", "search"]
    },
    {
      "id": "inventory.vehicle",
      "name": "Vehicle Detail",
      "description": "Return the detail view for a specific vehicle by VIN, stock, or vehicle_id.",
      "tags": ["inventory", "vehicle"]
    },
    {
      "id": "lead.submit",
      "name": "Submit Lead",
      "description": "Submit a consented lead carrying customer info plus any combination of vehicle of interest, trade-in, and appointment request.",
      "tags": ["lead", "submit", "vehicle", "trade-in", "appointment", "consent", "adf"]
    }
  ],
  "security_schemes": {},
  "security_requirements": []
}

Bearer-protected example (auth declaration only)

For a dealer agent that requires a bearer token, the security blocks change as follows. Skills, extensions, and supported_interfaces look identical.

{
  "security_schemes": {
    "bearer": {
      "type": "http",
      "scheme": "bearer",
      "bearer_format": "JWT"
    }
  },
  "security_requirements": [
    { "bearer": [] }
  ]
}

The contract manifest for this agent MUST set auth_type: "bearer".

What a buyer agent does next

Once the card is fetched and validated:

1. Read capabilities.extensions[].params.manifest_url and fetch the contract manifest. The manifest gives the buyer agent per-skill schema URLs and per-skill consent/anonymous flags.
2. Pick a binding from supported_interfaces[]. Both JSONRPC and HTTP+JSON accept the same AAP DataParts; choose whichever the buyer agent already speaks.
3. If security_requirements is non-empty, obtain a bearer token out of band before calling any skill.
4. Invoke skills via standard A2A SendMessage (JSON-RPC binding or REST binding).