# Introduction ![Buyer agents and dealer storefronts connected through typed AAP messages over A2A](https://autoagentprotocol.org/docs/v1.3/img/network-overview.svg) **The Auto Agent Protocol (AAP) lets AI assistants shop at car and motorcycle dealerships.** People increasingly ask an AI assistant to find their next car or motorcycle. AAP is the free, open standard that lets any of those assistants find a dealership, browse its real inventory, and — with the customer's clear permission — send the dealership a sales lead. Inventory listings carry an optional `vehicle_type` (`car`, `motorcycle`, `trailer`, `rv`, `other`; absent = `car`) so a single vocabulary covers both automotive and powersports retail, including electric models via a generic electric-powertrain field group. For a dealership, joining in means publishing **one small file on your own website** and answering a few well-defined questions; no app store, no middleman, no per-partner integration work. ![Dealers go live in three steps: publish the Agent Card, serve selected skills, and receive consented leads](https://autoagentprotocol.org/docs/v1.3/img/dealer-onboarding.svg) In technical terms: AAP is a strict [A2A v1.0](https://a2a-protocol.org/) (Agent2Agent) profile that defines the typed automotive data shapes AI agents and dealer agents exchange when they discover, browse, and submit leads. AAP does not invent a new wire protocol — every AAP message travels inside an A2A `Message.parts[].data` value as a typed `DataPart`. JSON-RPC 2.0 is the sole binding: a JSON-RPC 2.0 interface is REQUIRED on every AAP agent card. The HTTP+JSON (REST) binding was removed in v1.1.0, and gRPC is out of scope. The extension is identified by a single URI: ``` https://autoagentprotocol.org/extensions/aap/v1.3 ``` 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 ![Five AAP skills cover dealership information, inventory discovery, search, vehicle detail, and consented leads](https://autoagentprotocol.org/docs/v1.3/img/skills-overview.svg) AAP v1.3.0 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. | Skill | Purpose | |---|---| | `dealer.information` | Dealership profile, rooftops, hours, contact channels, capabilities | | `inventory.facets` | Aggregated counts and ranges over the dealer's inventory | | `inventory.search` | Filtered, paginated inventory queries (cars and motorcycles) | | `inventory.vehicle` | Detail view of one specific vehicle or motorcycle (by VIN, stock, or vehicle_id) | | `lead.submit` | Unified consented lead carrying customer info plus optional vehicle of interest, trade-in, and appointment | It does NOT define authentication (v1.3.0 agents are public by default; auth is left to A2A), payments, financing approval, RFQ/quote workflows, trade-in valuations, or reservations. Future versions MAY extend this surface; v1.3.0 is intentionally minimal. ## Layered architecture ![AAP typed automotive payloads profile A2A v1.0, which is carried over HTTPS](https://autoagentprotocol.org/docs/v1.3/img/architecture-stack.svg) 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. ```mermaid flowchart TB subgraph Buyer["Buyer agent (LLM, assistant, app)"] BA["AAP DataPart
<scope>.<thing>.request"] end subgraph A2A["A2A v1.0"] direction LR JR["JSON-RPC 2.0 binding (sole binding)"] end subgraph Dealer["Dealer agent"] DA["AAP DataPart
<scope>.<thing>.response"] end Buyer -->|A2A Message.parts| A2A A2A -->|HTTP POST| Dealer Dealer -->|A2A Message.parts| A2A A2A -->|HTTP response| Buyer ``` AAP uses exactly **one** A2A operation: `SendMessage` — a request `Message` goes in, a response `Message` comes out. The optional A2A surface (`SendStreamingMessage`, the `tasks` operations Get/List/Cancel/Subscribe, push notification configs, `GetExtendedAgentCard`) is out of scope for AAP: dealer agents do not need to implement it, and buyer agents MUST NOT require it. 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: ```bash curl https://demo-toyota.example.com/.well-known/agent-card.json ``` Confirm the card lists the AAP extension URI under `capabilities.extensions[].uri` and includes a `supportedInterfaces[]` entry whose `protocolBinding` is `JSONRPC` (REQUIRED on every AAP agent card; it is the sole AAP binding). ### 2. The binding Every AAP agent exposes the JSON-RPC 2.0 binding — AAP's sole transport. gRPC is out of scope, and the HTTP+JSON (REST) binding was removed in v1.1.0. | Binding | Status | A2A spec | AAP page | |---|---|---|---| | JSON-RPC 2.0 | REQUIRED (sole binding) | A2A Section 9 | [JSON-RPC binding](https://autoagentprotocol.org/docs/v1.3/bindings/json-rpc.md) | ### 3. Send a typed AAP message Wrap an AAP request inside an A2A `Message` and send it with `SendMessage` — the single A2A operation AAP uses. Below is the simplest call — `dealer.information` over the JSON-RPC binding, using the A2A v1.0 ProtoJSON wire format (`ROLE_USER`/`ROLE_AGENT` enum names, no `kind` discriminators) that A2A v1.0 clients send and parse: ```bash curl -X POST https://demo-toyota.example.com/a2a \ -H "Content-Type: application/json" \ -d '{ "jsonrpc": "2.0", "id": 1, "method": "SendMessage", "params": { "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 a `SendMessageResponse` in the JSON-RPC `result` — `{ "message": }` — where the `message` is an A2A `Message` whose first `DataPart.data` is an AAP response: ```json { "jsonrpc": "2.0", "id": 1, "result": { "message": { "messageId": "01HZ9G5P2KA8RT9WMS3B4C5D6E", "role": "ROLE_AGENT", "parts": [ { "data": { "type": "dealer.information.response", "data": { "name": "Demo Auto Group", "welcome_message": "Welcome to Demo Auto Group.", "rooftops": [ { "name": "Demo Toyota San Francisco", "legal_name": "Demo Toyota of San Francisco, LLC", "website": "https://demo-toyota.example.com", "phones": [ { "name": "Sales", "value": "+14155550100" } ], "address": { "country": "US", "state": "CA", "city": "San Francisco", "address_line_1": "100 Market St", "zip": "94105" }, "timezone": "America/Los_Angeles", "capabilities": [ "sales", "service", "financing" ] } ] } }, "mediaType": "application/vnd.autoagent.dealer-information-response+json" } ] } } } ``` ## Verified interoperability ![Verified JavaScript and Python A2A clients invoking the AAP dealer skill surface](https://autoagentprotocol.org/docs/v1.3/img/interop-clients.svg) All five skills have been exercised live through the official A2A v1.0 SDKs (`@a2a-js/sdk` and `a2a-sdk` for Python): inventory search, facets, vehicle detail, dealer information, and a consented `lead.submit` — with no AAP-specific client code. ## Where to read next - [Why automotive needs AAP](https://autoagentprotocol.org/docs/v1.3/why.md) — the gap AAP fills against A2A, ACP, MCP, and ADF. - [A2A profile](https://autoagentprotocol.org/docs/v1.3/a2a-profile.md) — how AAP slots into A2A's three-layer architecture. - [Discovery](https://autoagentprotocol.org/docs/v1.3/discovery.md) — full agent card example. - [Pricing and fee disclosure](https://autoagentprotocol.org/docs/v1.3/pricing-and-ftc.md) — authoritative price semantics, optional vehicle fee itemization, provider mapping, and current FTC context. - [Skills reference](https://autoagentprotocol.org/docs/v1.3/skills/dealer-information.md) — one page per skill with full request/response examples.