教程：构建一个使用工具的智能体

# 第 1 环：单个工具，单轮对话。

import json

import anthropic

# 创建客户端。它会从环境变量中读取 ANTHROPIC_API_KEY。
client = anthropic.Anthropic()

# 定义一个工具。input_schema 是一个 JSON Schema 对象，用于描述
# Claude 调用此工具时应传递的参数。此 schema
# 包含嵌套对象（recurrence）、数组（attendees）和可选
# 字段，这比扁平的字符串参数更接近真实世界的工具。
tools = [
    {
        "name": "create_calendar_event",
        "description": "Create a calendar event with attendees and optional recurrence.",
        "input_schema": {
            "type": "object",
            "properties": {
                "title": {"type": "string"},
                "start": {"type": "string", "format": "date-time"},
                "end": {"type": "string", "format": "date-time"},
                "attendees": {
                    "type": "array",
                    "items": {"type": "string", "format": "email"},
                },
                "recurrence": {
                    "type": "object",
                    "properties": {
                        "frequency": {"enum": ["daily", "weekly", "monthly"]},
                        "count": {"type": "integer", "minimum": 1},
                    },
                },
            },
            "required": ["title", "start", "end"],
        },
    }
]

# 将用户的请求连同工具定义一起发送。Claude 会根据
# 请求内容和工具描述来决定是否调用该工具。
response = client.messages.create(
    model="claude-opus-5",
    max_tokens=1024,
    tools=tools,
    tool_choice={"type": "auto", "disable_parallel_tool_use": True},
    messages=[
        {
            "role": "user",
            "content": "Schedule a 30-minute sync with [email protected] and [email protected] on Monday, March 30, 2026 at 10am.",
        }
    ],
)

# 当 Claude 调用工具时，响应的 stop_reason 为 "tool_use"，
# 并且 content 数组中会包含一个 tool_use 块以及可能的文本。
print(f"stop_reason: {response.stop_reason}")

# 查找 tool_use 块。响应中 tool_use 块之前可能包含文本块，
# 因此应遍历 content 数组，而不是假定其位置。
tool_use = next(block for block in response.content if block.type == "tool_use")
print(f"Tool: {tool_use.name}")
print(f"Input: {tool_use.input}")

# 执行工具。在真实系统中，这里会调用您的日历 API。
# 此处结果是硬编码的，以保持示例的自包含性。
result = {"event_id": "evt_123", "status": "created"}

# 将结果发回。tool_result 块需放在 user 消息中，
# 其 tool_use_id 必须与上面 tool_use 块中的 id 匹配。
# 同时包含助手的上一条响应，以便 Claude 拥有完整的历史记录。
followup = client.messages.create(
    model="claude-opus-5",
    max_tokens=1024,
    tools=tools,
    tool_choice={"type": "auto", "disable_parallel_tool_use": True},
    messages=[
        {
            "role": "user",
            "content": "Schedule a 30-minute sync with [email protected] and [email protected] on Monday, March 30, 2026 at 10am.",
        },
        {"role": "assistant", "content": response.content},
        {
            "role": "user",
            "content": [
                {
                    "type": "tool_result",
                    "tool_use_id": tool_use.id,
                    "content": json.dumps(result),
                }
            ],
        },
    ],
)

# 获得工具结果后，Claude 会生成最终的自然语言
# 回答，此时 stop_reason 变为 "end_turn"。
print(f"stop_reason: {followup.stop_reason}")
final_text = next(block for block in followup.content if block.type == "text")
print(final_text.text)

# 第 2 环：代理循环。

import json

import anthropic

client = anthropic.Anthropic()

tools = [
    {
        "name": "create_calendar_event",
        "description": "Create a calendar event with attendees and optional recurrence.",
        "input_schema": {
            "type": "object",
            "properties": {
                "title": {"type": "string"},
                "start": {"type": "string", "format": "date-time"},
                "end": {"type": "string", "format": "date-time"},
                "attendees": {
                    "type": "array",
                    "items": {"type": "string", "format": "email"},
                },
                "recurrence": {
                    "type": "object",
                    "properties": {
                        "frequency": {"enum": ["daily", "weekly", "monthly"]},
                        "count": {"type": "integer", "minimum": 1},
                    },
                },
            },
            "required": ["title", "start", "end"],
        },
    }
]


def run_tool(name, tool_input):
    if name == "create_calendar_event":
        return {"event_id": "evt_123", "status": "created", "title": tool_input["title"]}
    return {"error": f"Unknown tool: {name}"}


# 将完整的对话历史保存在列表中，以便每一轮都能看到先前的上下文。
messages = [
    {
        "role": "user",
        "content": "Schedule a weekly team standup every Monday at 9am for the next 4 weeks. Invite the whole team: [email protected], [email protected], [email protected].",
    }
]

response = client.messages.create(
    model="claude-opus-5",
    max_tokens=1024,
    tools=tools,
    tool_choice={"type": "auto", "disable_parallel_tool_use": True},
    messages=messages,
)

# 循环直到 Claude 不再请求工具。每次迭代运行所请求的
# 工具，将结果追加到历史记录中，然后让 Claude 继续。
while response.stop_reason == "tool_use":
    tool_use = next(block for block in response.content if block.type == "tool_use")
    result = run_tool(tool_use.name, tool_use.input)

    messages.append({"role": "assistant", "content": response.content})
    messages.append(
        {
            "role": "user",
            "content": [
                {
                    "type": "tool_result",
                    "tool_use_id": tool_use.id,
                    "content": json.dumps(result),
                }
            ],
        }
    )

    response = client.messages.create(
        model="claude-opus-5",
        max_tokens=1024,
        tools=tools,
        tool_choice={"type": "auto", "disable_parallel_tool_use": True},
        messages=messages,
    )

final_text = next(block for block in response.content if block.type == "text")
print(final_text.text)

# 第 3 环：多个工具，并行调用。

import json

import anthropic

client = anthropic.Anthropic()

tools = [
    {
        "name": "create_calendar_event",
        "description": "Create a calendar event with attendees and optional recurrence.",
        "input_schema": {
            "type": "object",
            "properties": {
                "title": {"type": "string"},
                "start": {"type": "string", "format": "date-time"},
                "end": {"type": "string", "format": "date-time"},
                "attendees": {
                    "type": "array",
                    "items": {"type": "string", "format": "email"},
                },
                "recurrence": {
                    "type": "object",
                    "properties": {
                        "frequency": {"enum": ["daily", "weekly", "monthly"]},
                        "count": {"type": "integer", "minimum": 1},
                    },
                },
            },
            "required": ["title", "start", "end"],
        },
    },
    {
        "name": "list_calendar_events",
        "description": "List all calendar events on a given date.",
        "input_schema": {
            "type": "object",
            "properties": {
                "date": {"type": "string", "format": "date"},
            },
            "required": ["date"],
        },
    },
]


def run_tool(name, tool_input):
    if name == "create_calendar_event":
        return {"event_id": "evt_123", "status": "created", "title": tool_input["title"]}
    if name == "list_calendar_events":
        return {"events": [{"title": "Existing meeting", "start": "14:00", "end": "15:00"}]}
    return {"error": f"Unknown tool: {name}"}


messages = [
    {
        "role": "user",
        "content": "Check what I have next Monday, then schedule a planning session that avoids any conflicts.",
    }
]

response = client.messages.create(
    model="claude-opus-5",
    max_tokens=1024,
    tools=tools,
    messages=messages,
)

while response.stop_reason == "tool_use":
    # 单个响应可以包含多个 tool_use 块。处理所有这些块，
    # 并将所有结果一起放在一条用户消息中返回。
    tool_results = []
    for block in response.content:
        if block.type == "tool_use":
            result = run_tool(block.name, block.input)
            tool_results.append(
                {
                    "type": "tool_result",
                    "tool_use_id": block.id,
                    "content": json.dumps(result),
                }
            )

    messages.append({"role": "assistant", "content": response.content})
    messages.append({"role": "user", "content": tool_results})

    response = client.messages.create(
        model="claude-opus-5",
        max_tokens=1024,
        tools=tools,
        messages=messages,
    )

final_text = next(block for block in response.content if block.type == "text")
print(final_text.text)

# 第 4 环：错误处理。

import json

import anthropic

client = anthropic.Anthropic()

tools = [
    {
        "name": "create_calendar_event",
        "description": "Create a calendar event with attendees and optional recurrence.",
        "input_schema": {
            "type": "object",
            "properties": {
                "title": {"type": "string"},
                "start": {"type": "string", "format": "date-time"},
                "end": {"type": "string", "format": "date-time"},
                "attendees": {
                    "type": "array",
                    "items": {"type": "string", "format": "email"},
                },
                "recurrence": {
                    "type": "object",
                    "properties": {
                        "frequency": {"enum": ["daily", "weekly", "monthly"]},
                        "count": {"type": "integer", "minimum": 1},
                    },
                },
            },
            "required": ["title", "start", "end"],
        },
    },
    {
        "name": "list_calendar_events",
        "description": "List all calendar events on a given date.",
        "input_schema": {
            "type": "object",
            "properties": {
                "date": {"type": "string", "format": "date"},
            },
            "required": ["date"],
        },
    },
]


def run_tool(name, tool_input):
    if name == "create_calendar_event":
        if "attendees" in tool_input and len(tool_input["attendees"]) > 10:
            raise ValueError("Too many attendees (max 10)")
        return {"event_id": "evt_123", "status": "created", "title": tool_input["title"]}
    if name == "list_calendar_events":
        return {"events": [{"title": "Existing meeting", "start": "14:00", "end": "15:00"}]}
    raise ValueError(f"Unknown tool: {name}")


messages = [
    {
        "role": "user",
        "content": "Schedule an all-hands with everyone: " + ", ".join(f"user{i}@example.com" for i in range(15)),
    }
]

response = client.messages.create(
    model="claude-opus-5",
    max_tokens=1024,
    tools=tools,
    messages=messages,
)

while response.stop_reason == "tool_use":
    tool_results = []
    for block in response.content:
        if block.type == "tool_use":
            try:
                result = run_tool(block.name, block.input)
                tool_results.append(
                    {"type": "tool_result", "tool_use_id": block.id, "content": json.dumps(result)}
                )
            except Exception as exc:
                # 发出失败信号，以便 Claude 重试或请求澄清。
                tool_results.append(
                    {
                        "type": "tool_result",
                        "tool_use_id": block.id,
                        "content": str(exc),
                        "is_error": True,
                    }
                )

    messages.append({"role": "assistant", "content": response.content})
    messages.append({"role": "user", "content": tool_results})

    response = client.messages.create(
        model="claude-opus-5",
        max_tokens=1024,
        tools=tools,
        messages=messages,
    )

final_text = next(block for block in response.content if block.type == "text")
print(final_text.text)

# 第 5 环：Tool Runner SDK 抽象层。

import json

import anthropic
from anthropic import beta_tool

client = anthropic.Anthropic()


@beta_tool
def create_calendar_event(
    title: str,
    start: str,
    end: str,
    attendees: list[str] | None = None,
    recurrence: dict | None = None,
) -> str:
    """Create a calendar event with attendees and optional recurrence.

    Args:
        title: Event title.
        start: Start time in ISO 8601 format.
        end: End time in ISO 8601 format.
        attendees: Email addresses to invite.
        recurrence: Dict with 'frequency' (daily, weekly, monthly) and 'count'.
    """
    if attendees and len(attendees) > 10:
        raise ValueError("Too many attendees (max 10)")
    return json.dumps({"event_id": "evt_123", "status": "created", "title": title})


@beta_tool
def list_calendar_events(date: str) -> str:
    """List all calendar events on a given date.

    Args:
        date: Date in YYYY-MM-DD format.
    """
    return json.dumps({"events": [{"title": "Existing meeting", "start": "14:00", "end": "15:00"}]})


final_message = client.beta.messages.tool_runner(
    model="claude-opus-5",
    max_tokens=1024,
    tools=[create_calendar_event, list_calendar_events],
    messages=[
        {
            "role": "user",
            "content": "Check what I have next Monday, then schedule a planning session that avoids any conflicts.",
        }
    ],
).until_done()

for block in final_message.content:
    if block.type == "text":
        print(block.text)