查看 API 参考 获取可用参数的完整文档。

​
基本请求和响应

#!/bin/sh
curl https://api.anthropic.com/v1/messages \
     --header "x-api-key: $ANTHROPIC_API_KEY" \
     --header "anthropic-version: 2023-06-01" \
     --header "content-type: application/json" \
     --data \
'{
    "model": "claude-opus-4-20250514",
    "max_tokens": 1024,
    "messages": [
        {"role": "user", "content": "Hello, Claude"}
    ]
}'
JSON
{
  "id": "msg_01XFDUDYJgAACzvnptvVoYEL",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "Hello!"
    }
  ],
  "model": "claude-opus-4-20250514",
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 12,
    "output_tokens": 6
  }
}

​
多轮对话

Messages API 是无状态的，这意味着您总是需要向 API 发送完整的对话历史。您可以使用这种模式来逐步构建对话。早期的对话轮次不一定需要真正来自 Claude — 您可以使用合成的 assistant 消息。 
#!/bin/sh
curl https://api.anthropic.com/v1/messages \
     --header "x-api-key: $ANTHROPIC_API_KEY" \
     --header "anthropic-version: 2023-06-01" \
     --header "content-type: application/json" \
     --data \
'{
    "model": "claude-opus-4-20250514",
    "max_tokens": 1024,
    "messages": [
        {"role": "user", "content": "Hello, Claude"},
        {"role": "assistant", "content": "Hello!"},
        {"role": "user", "content": "Can you describe LLMs to me?"}

    ]
}'
JSON
{
    "id": "msg_018gCsTGsXkYJVqYPxTgDHBU",
    "type": "message",
    "role": "assistant",
    "content": [
        {
            "type": "text",
            "text": "Sure, I'd be happy to provide..."
        }
    ],
    "stop_reason": "end_turn",
    "stop_sequence": null,
    "usage": {
      "input_tokens": 30,
      "output_tokens": 309
    }
}

​
为 Claude 预填回复

您可以在输入消息列表的最后位置预填 Claude 回复的一部分。这可以用来塑造 Claude 的回复。下面的示例使用 "max_tokens": 1 来从 Claude 获得单个选择题答案。 
#!/bin/sh
curl https://api.anthropic.com/v1/messages \
     --header "x-api-key: $ANTHROPIC_API_KEY" \
     --header "anthropic-version: 2023-06-01" \
     --header "content-type: application/json" \
     --data \
'{
    "model": "claude-opus-4-20250514",
    "max_tokens": 1,
    "messages": [
        {"role": "user", "content": "What is latin for Ant? (A) Apoidea, (B) Rhopalocera, (C) Formicidae"},
        {"role": "assistant", "content": "The answer is ("}
    ]
}'
JSON
{
  "id": "msg_01Q8Faay6S7QPTvEUUQARt7h",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "C"
    }
  ],
  "model": "claude-opus-4-20250514",
  "stop_reason": "max_tokens",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 42,
    "output_tokens": 1
  }
}

​
视觉

Claude 可以读取请求中的文本和图像。我们支持图像的 base64 和 url 源类型，以及 image/jpeg、image/png、image/gif 和 image/webp 媒体类型。查看我们的视觉指南了解更多详情。 
#!/bin/sh

# 选项 1：Base64 编码的图像
IMAGE_URL="https://upload.wikimedia.org/wikipedia/commons/a/a7/Camponotus_flavomarginatus_ant.jpg"
IMAGE_MEDIA_TYPE="image/jpeg"
IMAGE_BASE64=$(curl "$IMAGE_URL" | base64)

curl https://api.anthropic.com/v1/messages \
     --header "x-api-key: $ANTHROPIC_API_KEY" \
     --header "anthropic-version: 2023-06-01" \
     --header "content-type: application/json" \
     --data \
'{
    "model": "claude-opus-4-20250514",
    "max_tokens": 1024,
    "messages": [
        {"role": "user", "content": [
            {"type": "image", "source": {
                "type": "base64",
                "media_type": "'$IMAGE_MEDIA_TYPE'",
                "data": "'$IMAGE_BASE64'"
            }},
            {"type": "text", "text": "What is in the above image?"}
        ]}
    ]
}'

# 选项 2：URL 引用的图像
curl https://api.anthropic.com/v1/messages \
     --header "x-api-key: $ANTHROPIC_API_KEY" \
     --header "anthropic-version: 2023-06-01" \
     --header "content-type: application/json" \
     --data \
'{
    "model": "claude-opus-4-20250514",
    "max_tokens": 1024,
    "messages": [
        {"role": "user", "content": [
            {"type": "image", "source": {
                "type": "url",
                "url": "https://upload.wikimedia.org/wikipedia/commons/a/a7/Camponotus_flavomarginatus_ant.jpg"
            }},
            {"type": "text", "text": "What is in the above image?"}
        ]}
    ]
}'
JSON
{
  "id": "msg_01EcyWo6m4hyW8KHs2y2pei5",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "This image shows an ant, specifically a close-up view of an ant. The ant is shown in detail, with its distinct head, antennae, and legs clearly visible. The image is focused on capturing the intricate details and features of the ant, likely taken with a macro lens to get an extreme close-up perspective."
    }
  ],
  "model": "claude-opus-4-20250514",
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 1551,
    "output_tokens": 71
  }
}

​
工具使用、JSON 模式和计算机使用

查看我们的指南了解如何在 Messages API 中使用工具的示例。 查看我们的计算机使用指南了解如何使用 Messages API 控制桌面计算机环境的示例。