---
title: "Messages Native Conversation Interface"
description: "Claude Messages request headers, differences between system and messages, content blocks, and stop reasons."
headingIds: {"Minimal Request":"section-1","Request Structure":"section-2","Reading Content Blocks":"section-3","Multi-turn and Streaming":"section-4"}
---

<aside className="docs-publication" data-pagefind-ignore>

Documentation maintained by [1ZheAI](https://1zheai.com/en/editorial/#publisher). [Sources and corrections](https://1zheai.com/en/editorial/).

Found an error? [Contact support](mailto:support@1zheai.com) with the page address and a description. Do not send API keys or account credentials.

</aside>
Claude Code, the Anthropic SDK, and applications that want to preserve Claude's native content blocks use `POST https://1zheai.com/v1/messages`. Fill in the SDK Base URL with `https://1zheai.com`.

## Minimal Request

First set this site's key environment variable `ONEZHE_API_KEY`, then run:

```bash
curl --fail-with-body --connect-timeout 10 --max-time 120 \
  https://1zheai.com/v1/messages \
  -H "x-api-key: $ONEZHE_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-5-5",
    "max_tokens": 256,
    "system": "请用简短的中文回答。",
    "messages": [{"role": "user", "content": "什么是域名解析？"}]
  }'
```

## Request Structure

| Field | Type | Usage |
| --- | --- | --- |
| `model` | string | Required, selects the Claude model available to the key |
| `max_tokens` | integer | Required, output upper limit; set in combination with the selected model's limits |
| `messages` | array | Required, sends `user` and `assistant` messages in chronological order |
| `system` | string or array of content blocks | Optional, system instructions are placed at the top level, not as a `role: system` message |
| `stream` | boolean | Optional, streams content block increments |
| `tools` | array | Optional, declares tool names, purposes, and input Schemas |

`thinking`, cache control, and beta parameters depend on the specific model and upstream support. Verify plain text first, then add as needed; do not treat all models as having the same set of parameters.

## Reading Content Blocks

The returned `content` is an array and may contain text, tool requests, or other content blocks at the same time. Do not unconditionally read `content[0].text`. For example, using the Anthropic Python SDK:

```python
for block in message.content:
    if block.type == "text":
        print(block.text)
```

Here `message` comes from `client.messages.create(...)` in the [Anthropic SDK Tutorial ](/en/docs/quickstart-anthropic-sdk/).

| `stop_reason` | How the application should handle it |
| --- | --- |
| `end_turn` | This turn's answer has ended |
| `max_tokens` | Output was truncated by the upper limit and cannot be treated as a complete answer |
| `tool_use` | Check tool requests, execute permitted tools, and send back results |
| Other values | Keep the response and handle it according to the selected model's protocol; do not assume it is necessarily a text completion |

In a tool call loop, first add the complete assistant content block to history, then send it back with `tool_result` in the user content; `tool_use_id` must correspond to the original request. Do not convert tool requests directly into a single plain text passage.

## Multi-turn and Streaming

Send the history that needs to be retained each time; the interface itself does not store conversations for the application. Streaming uses `message_stop` to indicate the end of a message; receiving partial text does not mean the request has completed. See [Streaming Output ](/en/docs/streaming/) for details.

For protocol details, refer to [Anthropic Messages Usage Notes ](https://platform.claude.com/docs/en/build-with-claude/working-with-messages). Whether this site's extended parameters are available is determined by the model catalog and actual responses.