# Legacy REST binding The optional A2A HTTP+JSON interface was removed in **AAP 1.1**. This URL remains for historical links. AAP does not define a `POST /message:send` endpoint. Current interfaces: | Interface | Automotive calls | |---|---| | [MCP](https://autoagentprotocol.org/docs/v3.1/bindings/mcp.md) | Native tools over Streamable HTTP | | [A2A](https://autoagentprotocol.org/docs/v3.1/bindings/json-rpc.md) | `SendMessage` over JSON-RPC | | [PAP](https://autoagentprotocol.org/docs/v3.1/personal-agent-protocol.md) | Native OpenAPI operations with PAP Sessions and DPoP | PAP's automotive API is separate from the retired A2A HTTP+JSON option.