What is AP2？ • Orac1e の blog

智能体支付协议 (Agent Payments Protocol，AP2)是一个面向新兴代理经济的开放协议，该协议旨在为开发者、商户及支付行业提供安全可靠且互通互连的Agent商业解决方案。该协议作为开源的Agent2Agent（A2A）协议的扩展模块提供。

使用 ADK ↗ （或任何框架） 构建代理，配备 MCP ↗ （或任何工具） ，通过 A2A ↗ 进行协作，并使用 AP2 通过 gen AI 代理保障支付安全。

什么是Function calling?#

Agent：端到端（智能感知，决策，调用工具）解决问题

LLM只输出文本数据，缺乏工具运行的环境。OpenAI提出Function calling(also known as tool calling)—一种强大而灵活的方式来与外部系统交互，并访问训练数据之外的数据。

Function calling demo#

main.py

from rich.pretty import pprint
from openai import OpenAI
client = OpenAI(api_key="🤫", base_url="https://api.deepseek.com")

response = client.chat.completions.create(
    model="deepseek-chat",
    messages=[
        {"role": "user", "content": "9.11 - 9.9 = ?, Just tell me the answer."}
    ],
    stream=False
)

pprint(response)
print("=" * 100)
print(response.choices[0].message.content)

python

def subtraction(number1, number2): 
    return number1 - number2 

subtract_tool_description = { 
    "type": "function", 
    "function": { 
        "name": "subtraction", 
        "description": "number1减去number2", 
        "parameters": { 
            "type": "object", 
            "properties": { 
                "number1": {"type": "number"}, 
                "number2": {"type": "number"} 
            }, 
            "required": ["number1", "number2"] 
        } 
    } 
} 

response = client.chat.completions.create(
    model="deepseek-chat",
    tools=[subtract_tool_description], 
    messages=[
        {"role": "user", "content": "9.11 - 9.9 = ?, Just tell me the answer."}
    ],
    stream=False
)

python

模型训练时加入特殊标识的预料，使推理时返回正确格式的json

if response.choices[0].message.tool_calls:
    messages.append(response.choices[0].message)
    
    for tool_call in response.choices[0].message.tool_calls:
        args = json.loads(tool_call.function.arguments)
        result = subtraction(**args)
        messages.append({"role": "tool", "tool_call_id": tool_call.id, "content": str(result)})
    
    response = client.chat.completions.create(model="deepseek-chat", tools=tools, messages=messages)

print(response.choices[0].message.content)

python

什么是MCP？#

MCP 是一个开放协议，它为应用程序向 LLM 提供上下文的方式进行了标准化。你可以将 MCP 想象成 AI 应用程序的 USB-C 接口。就像 USB-C 为设备连接各种外设和配件提供了标准化的方式一样，MCP 为 AI 模型连接各种数据源和工具提供了标准化的接口。

MCP demo#

以Claude Desktop做Agent Client, 搭建Weather MCPserver

server.py

import json
import os
import httpx
from dotenv import load_dotenv
from typing import Any
from mcp.server.fastmcp import FastMCP

load_dotenv()

# 初始化 MCP 服务器
mcp = FastMCP("WeatherServer")

# OpenWeather API 配置
OPENWEATHER_API_BASE = "https://api.openweathermap.org/data/2.5/weather"
API_KEY = os.getenv("API_KEY")
USER_AGENT = "weather-app/1.0"


async def fetch_weather(city: str) -> dict[str, Any] | None:
    """
    从 OpenWeather API 获取天气信息。
    :param city: 城市名称（需使用英文，如 Beijing）
    :return: 天气数据字典；若出错返回包含 error 信息的字典
    """
    params = {
        "q": city,
        "appid": API_KEY,
        "units": "metric",
        "lang": "zh_cn"
    }
    headers = {"User-Agent": USER_AGENT}
    async with httpx.AsyncClient() as client:
        try:
            response = await client.get(
                OPENWEATHER_API_BASE,
                params=params,
                headers=headers,
                timeout=30.0
            )
            response.raise_for_status()
            return response.json()  # 返回字典类型
        except httpx.HTTPStatusError as e:
            return {"error": f"HTTP 错误: {e.response.status_code}"}
        except Exception as e:
            return {"error": f"请求失败: {str(e)}"}


def format_weather(data: dict[str, Any] | str) -> str:
    """
    将天气数据格式化为易读文本。
    :param data: 天气数据（可以是字典或 JSON 字符串）
    :return: 格式化后的天气信息字符串
    """
    # 如果传入的是字符串，则先转换为字典
    if isinstance(data, str):
        try:
            data = json.loads(data)
        except Exception as e:
            return f"无法解析天气数据: {e}"
    
    # 如果数据中包含错误信息，直接返回错误提示
    if "error" in data:
        return f"⚠️ {data['error']}"
    
    # 提取数据时做容错处理
    city = data.get("name", "未知")
    country = data.get("sys", {}).get("country", "未知")
    temp = data.get("main", {}).get("temp", "N/A")
    humidity = data.get("main", {}).get("humidity", "N/A")
    wind_speed = data.get("wind", {}).get("speed", "N/A")
    # weather 可能为空列表，因此用 [0] 前先提供默认字典
    weather_list = data.get("weather", [{}])
    description = weather_list[0].get("description", "未知")
    
    return (
        f"🌍 {city}, {country}\n"
        f"🌡 温度: {temp}°C\n"
        f"💧 湿度: {humidity}%\n"
        f"🌬 风速: {wind_speed} m/s\n"
        f"🌤 天气: {description}\n"
    )


@mcp.tool()
async def query_weather(city: str) -> str:
    """
    输入指定城市的英文名称，返回今日天气查询结果。
    :param city: 城市名称（需使用英文）
    :return: 格式化后的天气信息
    """
    data = await fetch_weather(city)
    return format_weather(data)


mcp.run(transport='stdio')

python

配置~/Library/Application Support/Claude/claude_desktop_config.json

claude_desktop_config.json

{
  "mcpServers": {
    "WeatherServer": {
      "command": "uv",
      "args": [
        "--directory",
        "/Users/byf/protocol/MCP",
        "run",
        "server.py"
      ]
    }
  }
}

json

2025-11-03T14:15:22.750Z [info] [WeatherServer] Initializing server...
2025-11-03T14:15:22.757Z [info] [WeatherServer] Using MCP server command: /opt/homebrew/bin/uv with args and path: {
  args: [
    '--directory',
    '/Users/byf/protocol/MCP',
    'run',
    'server.py',
    [length]: 4
  ],
  paths: [
    '/usr/local/bin',
    '/opt/homebrew/bin',
    '/usr/bin',
    '/usr/bin',
    '/bin',
    '/usr/sbin',
    '/sbin',
    [length]: 7
  ]
}
2025-11-03T14:15:22.758Z [info] [WeatherServer] Server started and connected successfully
2025-11-03T14:15:22.777Z [info] [WeatherServer] Message from client: {"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
2025-11-03T14:15:23.206Z [info] [WeatherServer] Message from server: {"jsonrpc":"2.0","id":0,"result":{"protocolVersion":"2025-06-18","capabilities":{"experimental":{},"prompts":{"listChanged":false},"resources":{"subscribe":false,"listChanged":false},"tools":{"listChanged":false}},"serverInfo":{"name":"WeatherServer","version":"1.20.0"}}}
2025-11-03T14:15:23.207Z [info] [WeatherServer] Message from client: {"method":"notifications/initialized","jsonrpc":"2.0"}
2025-11-03T14:15:23.207Z [info] [WeatherServer] Message from client: {"method":"tools/list","params":{},"jsonrpc":"2.0","id":1}
2025-11-03T14:15:23.207Z [info] [WeatherServer] Message from client: {"method":"prompts/list","params":{},"jsonrpc":"2.0","id":2}
2025-11-03T14:15:23.207Z [info] [WeatherServer] Message from client: {"method":"resources/list","params":{},"jsonrpc":"2.0","id":3}
2025-11-03T14:15:23.210Z [info] [WeatherServer] Message from server: {"jsonrpc":"2.0","id":1,"result":{"tools":[{"name":"query_weather","description":"\n输入指定城市的英文名称，返回今日天气查询结果。\n:param city: 城市名称（需使用英文）\n:return: 格式化后的天气信息\n","inputSchema":{"properties":{"city":{"title":"City","type":"string"}},"required":["city"],"title":"query_weatherArguments","type":"object"},"outputSchema":{"properties":{"result":{"title":"Result","type":"string"}},"required":["result"],"title":"query_weatherOutput","type":"object"}}]}}
2025-11-03T14:15:23.211Z [info] [WeatherServer] Message from server: {"jsonrpc":"2.0","id":2,"result":{"prompts":[]}}
2025-11-03T14:15:23.211Z [info] [WeatherServer] Message from server: {"jsonrpc":"2.0","id":3,"result":{"resources":[]}}

log

2025-11-03T14:42:20.342Z [info] [WeatherServer] Message from client: {"method":"tools/call","params":{"name":"query_weather","arguments":{"city":"Beijing"}},"jsonrpc":"2.0","id":4}
2025-11-03T14:42:20.964Z [info] [WeatherServer] Message from server: {"jsonrpc":"2.0","id":4,"result":{"content":[{"type":"text","text":"🌍 Beijing, CN\n🌡 温度: 4.94°C\n💧 湿度: 44%\n🌬 风速: 0.48 m/s\n🌤 天气: 晴\n"}],"structuredContent":{"result":"🌍 Beijing, CN\n🌡 温度: 4.94°C\n💧 湿度: 44%\n🌬 风速: 0.48 m/s\n🌤 天气: 晴\n"},"isError":false}}

log

什么是A2A？#

开发Agent的框架有很多，例如LangChain、Crewai、LlamaIndex、ADK等，A2A作为一种开放标准，旨在实现 AI Agent之间的无缝通信和协作。

互操作性：将基于不同平台（LangGraph、CrewAI、Semantic Kernel、自定义解决方案）构建的代理连接起来，创建强大的复合型人工智能系统。
复杂工作流程：使代理能够委派子任务、交换信息和协调行动，从而解决单个代理无法解决的复杂问题。
安全且不透明：代理之间无需共享内部内存、工具或专有逻辑即可进行交互，从而确保安全性并保护知识产权。

A2A demo#

a2aproject / a2a-samples

Waiting for api.github.com...

???

?????

基于Jsonrpc2.0和http协议实现客户端和服务端通信

每个Agent提供Agent Skills（描述了智能体可以执行的特定能力或功能）和Agent Cards（暴露在/.well-known/agent-card.json端点）

skill = AgentSkill(
    id='hello_world',
    name='Returns hello world',
    description='just returns hello world',
    tags=['hello world'],
    examples=['hi', 'hello world'],
)

# This will be the public-facing agent card
public_agent_card = AgentCard(
    name='Hello World Agent',
    description='Just a hello world agent',
    url='http://localhost:9999/',
    version='1.0.0',
    default_input_modes=['text'],
    default_output_modes=['text'],
    capabilities=AgentCapabilities(streaming=True),
    skills=[skill],  # Only the basic skill for the public card
    supports_authenticated_extended_card=True,
)

python

A2A Python SDK 提供了一个抽象基类a2a.server.agent_execution.AgentExecutor, 继承并实现Agent功能

客户端通过创建A2ACardResolver实例与服务端交互

base_url = 'http://localhost:9999'

async with httpx.AsyncClient() as httpx_client:
    # Initialize A2ACardResolver
    resolver = A2ACardResolver(
        httpx_client=httpx_client,
        base_url=base_url,
        # agent_card_path uses default, extended_agent_card_path also uses default
    )

send_message_payload: dict[str, Any] = {
    'message': {
        'role': 'user',
        'parts': [
            {'kind': 'text', 'text': 'how much is 10 USD in INR?'}
        ],
        'messageId': uuid4().hex,
    },
}
request = SendMessageRequest(
    id=str(uuid4()), params=MessageSendParams(**send_message_payload)
)

python

Agent 卡片发现（GET) > 功能调用（POST）

INFO:__main__:Attempting to fetch public agent card from: http://localhost:9999/.well-known/agent-card.json
INFO:httpx:HTTP Request: GET http://localhost:9999/.well-known/agent-card.json "HTTP/1.1 200 OK"
INFO:a2a.client.card_resolver:Successfully fetched agent card data from http://localhost:9999/.well-known/agent-card.json: {'capabilities': {'streaming': True}, 'defaultInputModes': ['text'], 'defaultOutputModes': ['text'], 'description': 'Just a hello world agent', 'name': 'Hello World Agent', 'preferredTransport': 'JSONRPC', 'protocolVersion': '0.3.0', 'skills': [{'description': 'just returns hello world', 'examples': ['hi', 'hello world'], 'id': 'hello_world', 'name': 'Returns hello world', 'tags': ['hello world']}], 'supportsAuthenticatedExtendedCard': True, 'url': 'http://localhost:9999/', 'version': '1.0.0'}
INFO:__main__:Successfully fetched public agent card:
INFO:__main__:{
  "capabilities": {
    "streaming": true
  },
  "defaultInputModes": [
    "text"
  ],
  "defaultOutputModes": [
    "text"
  ],
  "description": "Just a hello world agent",
  "name": "Hello World Agent",
  "preferredTransport": "JSONRPC",
  "protocolVersion": "0.3.0",
  "skills": [
    {
      "description": "just returns hello world",
      "examples": [
        "hi",
        "hello world"
      ],
      "id": "hello_world",
      "name": "Returns hello world",
      "tags": [
        "hello world"
      ]
    }
  ],
  "supportsAuthenticatedExtendedCard": true,
  "url": "http://localhost:9999/",
  "version": "1.0.0"
}
INFO:__main__:
Using PUBLIC agent card for client initialization (default).
INFO:__main__:
Public card supports authenticated extended card. Attempting to fetch from: http://localhost:9999/agent/authenticatedExtendedCard
INFO:httpx:HTTP Request: GET http://localhost:9999/agent/authenticatedExtendedCard "HTTP/1.1 200 OK"
INFO:a2a.client.card_resolver:Successfully fetched agent card data from http://localhost:9999/agent/authenticatedExtendedCard: {'capabilities': {'streaming': True}, 'defaultInputModes': ['text'], 'defaultOutputModes': ['text'], 'description': 'The full-featured hello world agent for authenticated users.', 'name': 'Hello World Agent - Extended Edition', 'preferredTransport': 'JSONRPC', 'protocolVersion': '0.3.0', 'skills': [{'description': 'just returns hello world', 'examples': ['hi', 'hello world'], 'id': 'hello_world', 'name': 'Returns hello world', 'tags': ['hello world']}, {'description': 'A more enthusiastic greeting, only for authenticated users.', 'examples': ['super hi', 'give me a super hello'], 'id': 'super_hello_world', 'name': 'Returns a SUPER Hello World', 'tags': ['hello world', 'super', 'extended']}], 'supportsAuthenticatedExtendedCard': True, 'url': 'http://localhost:9999/', 'version': '1.0.1'}
INFO:__main__:Successfully fetched authenticated extended agent card:
INFO:__main__:{
  "capabilities": {
    "streaming": true
  },
  "defaultInputModes": [
    "text"
  ],
  "defaultOutputModes": [
    "text"
  ],
  "description": "The full-featured hello world agent for authenticated users.",
  "name": "Hello World Agent - Extended Edition",
  "preferredTransport": "JSONRPC",
  "protocolVersion": "0.3.0",
  "skills": [
    {
      "description": "just returns hello world",
      "examples": [
        "hi",
        "hello world"
      ],
      "id": "hello_world",
      "name": "Returns hello world",
      "tags": [
        "hello world"
      ]
    },
    {
      "description": "A more enthusiastic greeting, only for authenticated users.",
      "examples": [
        "super hi",
        "give me a super hello"
      ],
      "id": "super_hello_world",
      "name": "Returns a SUPER Hello World",
      "tags": [
        "hello world",
        "super",
        "extended"
      ]
    }
  ],
  "supportsAuthenticatedExtendedCard": true,
  "url": "http://localhost:9999/",
  "version": "1.0.1"
}
INFO:__main__:
Using AUTHENTICATED EXTENDED agent card for client initialization.
/Users/byf/protocol/a2a-samples/samples/python/agents/helloworld/test_client.py:105: DeprecationWarning: A2AClient is deprecated and will be removed in a future version. Use ClientFactory to create a client with a JSON-RPC transport.
  client = A2AClient(
INFO:__main__:A2AClient initialized.
INFO:httpx:HTTP Request: POST http://localhost:9999/ "HTTP/1.1 200 OK"
{'id': 'f5311fd5-2fd7-44fd-8665-24181c6d7a20', 'jsonrpc': '2.0', 'result': {'kind': 'message', 'messageId': '14152c5a-74ef-4e1a-a6b8-603d125c229b', 'parts': [{'kind': 'text', 'text': 'Hello World'}], 'role': 'agent'}}
INFO:httpx:HTTP Request: POST http://localhost:9999/ "HTTP/1.1 200 OK"
{'id': '0ab0f29f-540b-4f3b-a583-71fc930382a7', 'jsonrpc': '2.0', 'result': {'kind': 'message', 'messageId': '36636649-25f0-4ad2-be34-70a195d45502', 'parts': [{'kind': 'text', 'text': 'Hello World'}], 'role': 'agent'}}

log

什么是AP2#

A2A 和 MCP 为 AI 代理提供了基础的通信和交互层，使它们能够连接和执行任务。AP2 以这些层为基础，添加了专门的安全支付扩展

当今的支付系统假设人类直接在受信任的网站上点击“购买”。当自主代理发起支付时，这个核心假设被打破，导致当前系统无法回答的关键问题：

授权： 我们如何验证用户是否为代理授予特定购买的特定权限？
真实性： 商家如何确保代理的请求准确反映用户的真实意图，而不会出现错误或人工智能“幻觉”？
问责： 如果发生欺诈或不正确的交易，谁应该负责——用户、代理的开发者、商家还是发卡机构？

机制#

Role-Based Architecture

用户：将付款任务委派给代理的个人。

用户代理（UA） / 购物代理（SA）：与用户交互的 AI 表面（例如 Gemini、ChatGPT）。它了解用户的需求，构建购物车，并获得用户的授权。

凭证提供者（CP）：安全管理用户支付凭证和方法的专门实体（例如数字钱包）。

商家端点（ME）：代表商家作的界面或代理，用于展示产品和协商购物车。

商户支付处理器端点（MPP）：为支付网络构建最终交易授权消息的实体。

网络和发卡机构：支付网络和颁发用户支付凭证的金融机构。

可验证的数字凭证（VDC）

实时购买 (Human Present)

「帮我找双新的白色跑鞋」

用户的请求会被记录在初始意向授权中。这为整个交易流程中的交互提供了可审计的背景信息。当 Agent 将用户想要的鞋子放在购物车中后，由商家生成并由用户进行加密签名，将创建商品明细与价格的防篡改记录，确保所见即所付。

生命周期 ↗

2.委托购买（Human Not Present）

「演唱会门票一经发售立即购买」

由购物代理提前生成凭证并由用户签名，授予代理在定义的约束内行事的权限。该授权书详细规定了参与规则 —— 价格限制、时间安排和其他条件。它将作为可验证的预授权凭证，一旦满足用户的具体条件，Agent 便可自动为用户生成购物车授权书。

付款授权独立的VDC，与支付网络和发卡机构共享。

目的是提供交易的可见性，帮助网络和发卡机构建立信任并评估风险。它包含人工智能代理是否参与以及交易模式（有人在场或无人在场）的信号。

AP2 demo#

google-agentic-commerce / AP2

Waiting for api.github.com...

???

?????

包含四个主要Agent，shopping Agent（与用户交互）、CredentialsProvider（提供凭证）、MerchantAgent（提供商品）、merchant_payment_processor_agent

主Agent部分日志，查看交互细节

CredentialsProvider listening on http://localhost:8002
merchant_payment_processor_agent listening on http://localhost:8003
MerchantAgent listening on http://localhost:8001




---------- New Agent Request Received---------
GET http://localhost:8001/a2a/merchant_agent/.well-known/agent-card.json


[Request Body]
<empty>


[Response Body]
{"capabilities":{"extensions":[{"description":"Supports the Agent Payments Protocol.","required":true,"uri":"https://github.com/google-agentic-commerce/ap2/v1"},{"description":"Supports the Sample Card Network payment method extension","required":true,"uri":"https://sample-card-network.github.io/paymentmethod/types/v1"}]},"defaultInputModes":["json"],"defaultOutputModes":["json"],"description":"A sales assistant agent for a merchant.","name":"MerchantAgent","preferredTransport":"JSONRPC","protocolVersion":"0.3.0","skills":[{"description":"Searches the merchant's catalog based on a shopping intent & returns a cart containing the top results.","id":"search_catalog","name":"Search Catalog","tags":["merchant","search","catalog"]}],"url":"http://localhost:8001/a2a/merchant_agent","version":"1.0.0"}




---------- New Agent Request Received---------
POST http://localhost:8001/a2a/merchant_agent


[Request Body]
{'id': '8d19c85a-53d6-4216-a280-9cf16868392d', 'jsonrpc': '2.0', 'method': 'message/send', 'params': {'configuration': {'acceptedOutputModes': [], 'blocking': True}, 'message': {'kind': 'message', 'messageId': 'b3526bfb92174b618bf2a98e5c8a26c0', 'parts': [{'kind': 'text', 'text': "Find products that match the user's IntentMandate."}, {'data': {'ap2.mandates.IntentMandate': {'user_cart_confirmation_required': True, 'natural_language_description': 'a coffee maker', 'merchants': [], 'skus': [], 'requires_refundability': True, 'intent_expiry': '2025-11-05T09:58:02.506702+00:00'}}, 'kind': 'data'}, {'data': {'risk_data': 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...fake_risk_data'}, 'kind': 'data'}, {'data': {'shopping_agent_id': 'trusted_shopping_agent'}, 'kind': 'data'}], 'role': 'agent'}}}

[Extension Header]
X-A2A-Extensions: https://github.com/google-agentic-commerce/ap2/v1


[Request Instructions]
["Find products that match the user's IntentMandate."]


[An Intent Mandate was in the request Data]
{'user_cart_confirmation_required': True, 'natural_language_description': 'a coffee maker', 'merchants': [], 'skus': [], 'requires_refundability': True, 'intent_expiry': '2025-11-05T09:58:02.506702+00:00'}


[Data Part: risk_data] 
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...fake_risk_data


[Data Part: shopping_agent_id] 
trusted_shopping_agent


[Response Body]
{"id":"8d19c85a-53d6-4216-a280-9cf16868392d","jsonrpc":"2.0","result":{"artifacts":[{"artifactId":"b1e19438-44e7-4a66-8b72-ed5ad468b843","parts":[{"data":{"ap2.mandates.CartMandate":{"contents":{"id":"cart_1","user_cart_confirmation_required":true,"payment_request":{"method_data":[{"supported_methods":"CARD","data":{"network":["mastercard","paypal","amex"]}}],"details":{"id":"order_1","display_items":[{"label":"Drip coffee maker","amount":{"currency":"USD","value":49.99},"pending":null,"refund_period":30}],"shipping_options":null,"modifiers":null,"total":{"label":"Total","amount":{"currency":"USD","value":49.99},"pending":null,"refund_period":30}},"options":{"request_payer_name":false,"request_payer_email":false,"request_payer_phone":false,"request_shipping":true,"shipping_type":null},"shipping_address":null},"cart_expiry":"2025-11-04T10:28:56.878832+00:00","merchant_name":"Generic Merchant"},"merchant_authorization":null}},"kind":"data"}]},{"artifactId":"b4977f03-c0fa-43ec-84d7-69e10b9832be","parts":[{"data":{"ap2.mandates.CartMandate":{"contents":{"id":"cart_2","user_cart_confirmation_required":true,"payment_request":{"method_data":[{"supported_methods":"CARD","data":{"network":["mastercard","paypal","amex"]}}],"details":{"id":"order_2","display_items":[{"label":"Single-serve coffee machine","amount":{"currency":"USD","value":89.0},"pending":false,"refund_period":30}],"shipping_options":null,"modifiers":null,"total":{"label":"Total","amount":{"currency":"USD","value":89.0},"pending":null,"refund_period":30}},"options":{"request_payer_name":false,"request_payer_email":false,"request_payer_phone":false,"request_shipping":true,"shipping_type":null},"shipping_address":null},"cart_expiry":"2025-11-04T10:28:56.878832+00:00","merchant_name":"Generic Merchant"},"merchant_authorization":null}},"kind":"data"}]},{"artifactId":"06e333b4-896b-4db7-a43e-d853e18a6b85","parts":[{"data":{"ap2.mandates.CartMandate":{"contents":{"id":"cart_3","user_cart_confirmation_required":true,"payment_request":{"method_data":[{"supported_methods":"CARD","data":{"network":["mastercard","paypal","amex"]}}],"details":{"id":"order_3","display_items":[{"label":"Pour-over coffee system","amount":{"currency":"USD","value":35.5},"pending":null,"refund_period":14}],"shipping_options":null,"modifiers":null,"total":{"label":"Total","amount":{"currency":"USD","value":35.5},"pending":null,"refund_period":30}},"options":{"request_payer_name":false,"request_payer_email":false,"request_payer_phone":false,"request_shipping":true,"shipping_type":null},"shipping_address":null},"cart_expiry":"2025-11-04T10:28:56.878832+00:00","merchant_name":"Generic Merchant"},"merchant_authorization":null}},"kind":"data"}]}],"contextId":"c2dba1b7-36a7-4727-87b3-031df46a4e9e","history":[{"contextId":"c2dba1b7-36a7-4727-87b3-031df46a4e9e","kind":"message","messageId":"b3526bfb92174b618bf2a98e5c8a26c0","parts":[{"kind":"text","text":"Find products that match the user's IntentMandate."},{"data":{"ap2.mandates.IntentMandate":{"user_cart_confirmation_required":true,"natural_language_description":"a coffee maker","merchants":[],"skus":[],"requires_refundability":true,"intent_expiry":"2025-11-05T09:58:02.506702+00:00"}},"kind":"data"},{"data":{"risk_data":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...fake_risk_data"},"kind":"data"},{"data":{"shopping_agent_id":"trusted_shopping_agent"},"kind":"data"}],"role":"agent","taskId":"2dd9352b-b8e3-448e-8cae-2873b1c459f3"}],"id":"2dd9352b-b8e3-448e-8cae-2873b1c459f3","kind":"task","status":{"state":"completed","timestamp":"2025-11-04T09:58:56.883469+00:00"}}}




---------- New Agent Request Received---------
GET http://localhost:8001/a2a/merchant_agent/.well-known/agent-card.json


[Request Body]
<empty>


[Response Body]
{"capabilities":{"extensions":[{"description":"Supports the Agent Payments Protocol.","required":true,"uri":"https://github.com/google-agentic-commerce/ap2/v1"},{"description":"Supports the Sample Card Network payment method extension","required":true,"uri":"https://sample-card-network.github.io/paymentmethod/types/v1"}]},"defaultInputModes":["json"],"defaultOutputModes":["json"],"description":"A sales assistant agent for a merchant.","name":"MerchantAgent","preferredTransport":"JSONRPC","protocolVersion":"0.3.0","skills":[{"description":"Searches the merchant's catalog based on a shopping intent & returns a cart containing the top results.","id":"search_catalog","name":"Search Catalog","tags":["merchant","search","catalog"]}],"url":"http://localhost:8001/a2a/merchant_agent","version":"1.0.0"}




---------- New Agent Request Received---------
POST http://localhost:8001/a2a/merchant_agent


[Request Body]
{'id': 'fab0d460-978f-470f-a126-8756f08a05bc', 'jsonrpc': '2.0', 'method': 'message/send', 'params': {'configuration': {'acceptedOutputModes': [], 'blocking': True}, 'message': {'contextId': 'c2dba1b7-36a7-4727-87b3-031df46a4e9e', 'kind': 'message', 'messageId': 'a0fdcf95dab344af870c1b87d4287c45', 'parts': [{'kind': 'text', 'text': "Update the cart with the user's shipping address."}, {'data': {'cart_id': 'cart_1'}, 'kind': 'data'}, {'data': {'shipping_address': {'city': 'Colorado Springs', 'region': 'Colorado', 'address_line': ['562 Berry Street'], 'postal_code': '80904'}}, 'kind': 'data'}, {'data': {'shopping_agent_id': 'trusted_shopping_agent'}, 'kind': 'data'}], 'role': 'agent'}}}

[Extension Header]
X-A2A-Extensions: https://github.com/google-agentic-commerce/ap2/v1


[Request Instructions]
["Update the cart with the user's shipping address."]


[Data Part: cart_id] 
cart_1


[Data Part: shipping_address] 
{'city': 'Colorado Springs', 'region': 'Colorado', 'address_line': ['562 Berry Street'], 'postal_code': '80904'}


[Data Part: shopping_agent_id] 
trusted_shopping_agent


[Response Body]
{"id":"fab0d460-978f-470f-a126-8756f08a05bc","jsonrpc":"2.0","result":{"artifacts":[{"artifactId":"ce7f4866-42ab-4b0a-81b9-92c9e9f95c56","parts":[{"data":{"ap2.mandates.CartMandate":{"contents":{"id":"cart_1","user_cart_confirmation_required":true,"payment_request":{"method_data":[{"supported_methods":"CARD","data":{"network":["mastercard","paypal","amex"]}}],"details":{"id":"order_1","display_items":[{"label":"Drip coffee maker","amount":{"currency":"USD","value":53.49},"pending":null,"refund_period":30},{"label":"Shipping","amount":{"currency":"USD","value":2.0},"pending":null,"refund_period":30},{"label":"Tax","amount":{"currency":"USD","value":1.5},"pending":null,"refund_period":30}],"shipping_options":null,"modifiers":null,"total":{"label":"Total","amount":{"currency":"USD","value":53.49},"pending":null,"refund_period":30}},"options":{"request_payer_name":false,"request_payer_email":false,"request_payer_phone":false,"request_shipping":true,"shipping_type":null},"shipping_address":{"city":"Colorado Springs","country":null,"dependent_locality":null,"organization":null,"phone_number":null,"postal_code":"80904","recipient":null,"region":"Colorado","sorting_code":null,"address_line":["562 Berry Street"]}},"cart_expiry":"2025-11-04T10:28:56.878832+00:00","merchant_name":"Generic Merchant"},"merchant_authorization":"eyJhbGciOiJSUzI1NiIsImtpZIwMjQwOTA..."}},"kind":"data"},{"data":{"risk_data":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...fake_risk_data"},"kind":"data"}]}],"contextId":"c2dba1b7-36a7-4727-87b3-031df46a4e9e","history":[{"contextId":"c2dba1b7-36a7-4727-87b3-031df46a4e9e","kind":"message","messageId":"a0fdcf95dab344af870c1b87d4287c45","parts":[{"kind":"text","text":"Update the cart with the user's shipping address."},{"data":{"cart_id":"cart_1"},"kind":"data"},{"data":{"shipping_address":{"city":"Colorado Springs","region":"Colorado","address_line":["562 Berry Street"],"postal_code":"80904"}},"kind":"data"},{"data":{"shopping_agent_id":"trusted_shopping_agent"},"kind":"data"}],"role":"agent","taskId":"b8090fb7-8b38-4552-a5f9-3fabab266483"}],"id":"b8090fb7-8b38-4552-a5f9-3fabab266483","kind":"task","status":{"state":"completed","timestamp":"2025-11-04T10:04:38.324489+00:00"}}}




---------- New Agent Request Received---------
GET http://localhost:8002/a2a/credentials_provider/.well-known/agent-card.json


[Request Body]
<empty>


[Response Body]
{"capabilities":{"extensions":[{"description":"Supports the Agent Payments Protocol.","required":true,"uri":"https://github.com/google-agentic-commerce/ap2/v1"},{"description":"Supports the Sample Card Network payment method extension","required":true,"uri":"https://sample-card-network.github.io/paymentmethod/types/v1"}]},"defaultInputModes":["text/plain"],"defaultOutputModes":["application/json"],"description":"An agent that holds a user's payment credentials.","name":"CredentialsProvider","preferredTransport":"JSONRPC","protocolVersion":"0.3.0","skills":[{"description":"Initiates a payment with the correct payment processor.","id":"initiate_payment","name":"Initiate Payment","tags":["payments"]},{"description":"Provides a list of eligible payment methods for a particular purchase.","id":"get_eligible_payment_methods","name":"Get Eligible Payment Methods","tags":["eligible","payment","methods"]},{"description":"Fetches the shipping address from a user's wallet.","id":"get_account_shipping_address","name":"Get Shipping Address","tags":["account","shipping"]}],"url":"http://localhost:8002/a2a/credentials_provider","version":"1.0.0"}




---------- New Agent Request Received---------
POST http://localhost:8002/a2a/credentials_provider


[Request Body]
{'id': '91b5a7de-0c92-4164-a4b2-e99a5595987c', 'jsonrpc': '2.0', 'method': 'message/send', 'params': {'configuration': {'acceptedOutputModes': [], 'blocking': True}, 'message': {'contextId': 'c2dba1b7-36a7-4727-87b3-031df46a4e9e', 'kind': 'message', 'messageId': 'f79087c80749404bbe5bff84b5c96fee', 'parts': [{'kind': 'text', 'text': "Get a filtered list of the user's payment methods."}, {'data': {'user_email': '[email protected]'}, 'kind': 'data'}, {'data': {'payment_request.PaymentMethodData': {'supported_methods': 'CARD', 'data': {'network': ['mastercard', 'paypal', 'amex']}}}, 'kind': 'data'}], 'role': 'agent'}}}

[Extension Header]
X-A2A-Extensions: https://github.com/google-agentic-commerce/ap2/v1


[Request Instructions]
["Get a filtered list of the user's payment methods."]


[Data Part: user_email] 
baoyf.jlu@gmail.com


[Data Part: payment_request.PaymentMethodData] 
{'supported_methods': 'CARD', 'data': {'network': ['mastercard', 'paypal', 'amex']}}


[Response Body]
{"id":"91b5a7de-0c92-4164-a4b2-e99a5595987c","jsonrpc":"2.0","result":{"artifacts":[{"artifactId":"caf579c9-ea28-4787-afcd-dad334448344","parts":[{"data":{"payment_method_aliases":[]},"kind":"data"}]}],"contextId":"c2dba1b7-36a7-4727-87b3-031df46a4e9e","history":[{"contextId":"c2dba1b7-36a7-4727-87b3-031df46a4e9e","kind":"message","messageId":"f79087c80749404bbe5bff84b5c96fee","parts":[{"kind":"text","text":"Get a filtered list of the user's payment methods."},{"data":{"user_email":"[email protected]"},"kind":"data"},{"data":{"payment_request.PaymentMethodData":{"supported_methods":"CARD","data":{"network":["mastercard","paypal","amex"]}}},"kind":"data"}],"role":"agent","taskId":"1f8cb70e-e657-4e1c-868e-3f0d8008b838"}],"id":"1f8cb70e-e657-4e1c-868e-3f0d8008b838","kind":"task","status":{"state":"completed","timestamp":"2025-11-04T10:08:16.749007+00:00"}}}

log

最终凭证状态

{
  "intent_mandate": {
    "user_cart_confirmation_required": true,
    "natural_language_description": "a coffee maker",
    "merchants": [],
    "skus": [],
    "requires_refundability": true,
    "intent_expiry": "2025-11-05T09:58:02.506702+00:00",
    "risk_data": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...fake_risk_data",
    "shopping_context_id": "c2dba1b7-36a7-4727-87b3-031df46a4e9e",
    "cart_mandates": [
      {
        "contents": {
          "id": "cart_1",
          "user_cart_confirmation_required": true,
          "payment_request": {
            "method_data": [
              {
                "supported_methods": "CARD",
                "data": {
                  "network": ["mastercard", "paypal", "amex"]
                }
              }
            ],
            "details": {
              "id": "order_1",
              "display_items": [
                {
                  "label": "Drip coffee maker",
                  "amount": {
                    "currency": "USD",
                    "value": 49.99
                  },
                  "refund_period": 30
                }
              ],
              "total": {
                "label": "Total",
                "amount": {
                  "currency": "USD",
                  "value": 49.99
                },
                "refund_period": 30
              }
            },
            "options": {
              "request_payer_name": false,
              "request_payer_email": false,
              "request_payer_phone": false,
              "request_shipping": true
            }
          },
          "cart_expiry": "2025-11-04T10:28:56.878832+00:00",
          "merchant_name": "Generic Merchant"
        }
      },
      {
        "contents": {
          "id": "cart_2",
          "user_cart_confirmation_required": true,
          "payment_request": {
            "method_data": [
              {
                "supported_methods": "CARD",
                "data": {
                  "network": ["mastercard", "paypal", "amex"]
                }
              }
            ],
            "details": {
              "id": "order_2",
              "display_items": [
                {
                  "label": "Single-serve coffee machine",
                  "amount": {
                    "currency": "USD",
                    "value": 89
                  },
                  "refund_period": 30
                }
              ],
              "total": {
                "label": "Total",
                "amount": {
                  "currency": "USD",
                  "value": 89
                },
                "refund_period": 30
              }
            },
            "options": {
              "request_payer_name": false,
              "request_payer_email": false,
              "request_payer_phone": false,
              "request_shipping": true
            }
          },
          "cart_expiry": "2025-11-04T10:28:56.878832+00:00",
          "merchant_name": "Generic Merchant"
        }
      },
      {
        "contents": {
          "id": "cart_3",
          "user_cart_confirmation_required": true,
          "payment_request": {
            "method_data": [
              {
                "supported_methods": "CARD",
                "data": {
                  "network": ["mastercard", "paypal", "amex"]
                }
              }
            ],
            "details": {
              "id": "order_3",
              "display_items": [
                {
                  "label": "Pour-over coffee system",
                  "amount": {
                    "currency": "USD",
                    "value": 35.5
                  },
                  "refund_period": 14
                }
              ],
              "total": {
                "label": "Total",
                "amount": {
                  "currency": "USD",
                  "value": 35.5
                },
                "refund_period": 30
              }
            },
            "options": {
              "request_payer_name": false,
              "request_payer_email": false,
              "request_payer_phone": false,
              "request_shipping": true
            }
          },
          "cart_expiry": "2025-11-04T10:28:56.878832+00:00",
          "merchant_name": "Generic Merchant"
        }
      }
    ],
    "chosen_cart_id": "cart_1",
    "cart_mandate": {
      "contents": {
        "id": "cart_1",
        "user_cart_confirmation_required": true,
        "payment_request": {
          "method_data": [
            {
              "supported_methods": "CARD",
              "data": {
                "network": ["mastercard", "paypal", "amex"]
              }
            }
          ],
          "details": {
            "id": "order_1",
            "display_items": [
              {
                "label": "Drip coffee maker",
                "amount": {
                  "currency": "USD",
                  "value": 53.49
                },
                "refund_period": 30
              },
              {
                "label": "Shipping",
                "amount": {
                  "currency": "USD",
                  "value": 2
                },
                "refund_period": 30
              },
              {
                "label": "Tax",
                "amount": {
                  "currency": "USD",
                  "value": 1.5
                },
                "refund_period": 30
              }
            ],
            "total": {
              "label": "Total",
              "amount": {
                "currency": "USD",
                "value": 53.49
              },
              "refund_period": 30
            }
          },
          "options": {
            "request_payer_name": false,
            "request_payer_email": false,
            "request_payer_phone": false,
            "request_shipping": true
          }
        },
        "shipping_address": {
          "city": "Colorado Springs",
          "region": "Colorado",
          "address_line": ["562 Berry Street"],
          "postal_code": "80904"
        },
        "cart_expiry": "2025-11-04T10:28:56.878832+00:00",
        "merchant_name": "Generic Merchant"
      }
    },
    "merchant_authorization": "eyJhbGciOiJSUzI1NiIsImtpZIwMjQwOTA...",
    "shipping_address": {
      "city": "Colorado Springs",
      "region": "Colorado",
      "address_line": ["562 Berry Street"],
      "postal_code": "80904"
    }
  }
}

json

参考#

「AI助手」真来了？谷歌牵头推进Agent支付协议AP2 ↗

Function Calling、MCP和A2A的核心原理与区别 ↗

Function calling & MCP for LLMs ↗

Model Context Protocol (MCP) ↗

OpenAI Platform — Function calling ↗

A2A Protocol ↗

AP2 - Agent Payments Protocol Documentation ↗