# Anthropic Messages

Anthropic Messages

## Endpoint and authentication

`POST https://api.tu-zi.com/v1/messages`

Transport: json

Use an inference API key. Examples contain placeholders; read credentials from environment variables.

```http
Authorization: Bearer YOUR_API_KEY
anthropic-version: 2023-06-01
Content-Type: application/json
```

## Body parameters

| Field | Type | Required | Description / constraints |
| --- | --- | --- | --- |
| model | string | Yes | Model name to call. Example: claude-3-7-sonnet |
| max_tokens | number | Yes | Required explicit Anthropic output token limit. Small limits can truncate output; larger limits may increase maximum time and cost without forcing longer output. Form initial value (not an upstream default): 512 Range in this definition: 1 ~ 128000 Example: 512 |
| messages | array | Yes | Conversation messages; content supports structured text blocks and other supported block types. Example: [{"role":"user","content":"你好"}] |
| stream | boolean | No | Whether to enable streaming responses. Form initial value (not an upstream default): false Example: false |
| temperature | number | No | Sampling temperature between 0 and 1. Form initial value (not an upstream default): 0.7 Range in this definition: 0 ~ 1 Example: 0.7 |
| top_p | number | No | Nucleus sampling probability threshold. Form initial value (not an upstream default): 1 Range in this definition: 0 ~ 1 Example: 0.9 |
| top_k | number | No | Sample only from the K most probable tokens. Range in this definition: 1 ~ 500 Example: 40 |
| messages[].role | string | No | user or assistant. System instructions belong in top-level system. |
| messages[].content | string \| array | No | Text or text/image/tool_use/tool_result blocks. |
| tools | array | No | Tool definitions contain name, description and input_schema. |

## Minimal request example

```json
{
  "model": "YOUR_MODEL",
  "max_tokens": 512,
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ]
}
```

## Before running

Replace https://api.tu-zi.com with this site origin (do not append /v1 twice), and YOUR_MODEL with the exact marketplace model ID. Install requests for Python; use Node.js 20+ and save JavaScript as .mjs. WebSocket samples list their own dependencies.

Create an inference key on the site and set API_KEY in the environment; replace YOUR_API_KEY in cURL. Prepare local input.png/input.wav files for upload examples.

Start with a minimal request, then read the result using the response fields below. For async APIs, a returned task ID requires polling; acceptance does not mean generation has finished.

## Code examples

### curl

```bash
curl --request POST 'https://api.tu-zi.com/v1/messages' \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'anthropic-version: 2023-06-01' \
  --header 'Content-Type: application/json' \
  --data '{
  "model": "YOUR_MODEL",
  "max_tokens": 512,
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ]
}'
```

### python

```python
import json
import os
import requests

url = "https://api.tu-zi.com/v1/messages"
headers = json.loads("{\"Authorization\":\"Bearer YOUR_API_KEY\",\"anthropic-version\":\"2023-06-01\",\"Content-Type\":\"application/json\"}")
headers["Authorization"] = "Bearer " + os.environ["API_KEY"]
payload = json.loads("{\"model\":\"YOUR_MODEL\",\"max_tokens\":512,\"messages\":[{\"role\":\"user\",\"content\":\"Hello\"}]}")
response = requests.request("POST", url, headers=headers, json=payload, timeout=120)
response.raise_for_status()
result = response.json()
if isinstance(result, dict) and (result.get("success") is False or result.get("error")):
    raise RuntimeError(json.dumps(result, ensure_ascii=False))
print(result)  # Also inspect protocol-specific status/code fields.
```

### javascript

```javascript
// Node.js 20+
const url = "https://api.tu-zi.com/v1/messages";
const headers = {
  "Authorization": "Bearer YOUR_API_KEY",
  "anthropic-version": "2023-06-01",
  "Content-Type": "application/json"
};
headers.Authorization = 'Bearer ' + process.env.API_KEY;
const response = await fetch(url, { method: "POST", headers, body: JSON.stringify({
  "model": "YOUR_MODEL",
  "max_tokens": 512,
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ]
}) });
if (!response.ok) throw new Error(await response.text());
const result = await response.json();
if (result?.success === false || result?.error) throw new Error(JSON.stringify(result));
console.log(result); // Also inspect protocol-specific status/code fields.
```

## Response fields

| Field | Type | Description / constraints |
| --- | --- | --- |
| content[] | object | Content blocks such as text and tool_use. |
| stop_reason | string | Stop reason. |
| usage | object | input_tokens and output_tokens. |

Illustrative response; some endpoints show essential fields only. Optional fields may be absent.

```json
{
  "id": "msg_example",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "Hello"
    }
  ],
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 5,
    "output_tokens": 1
  }
}
```

## Streaming

With stream=true handle message_start, content_block_delta, message_delta and message_stop SSE events.

## Errors and retries

Check HTTP status and protocol-specific errors; do not mix error formats across protocols. For 401/403 check credentials and permissions, for 429 back off, and for 5xx check gateway/upstream status. Error bodies may contain error/message/code depending on the protocol.

Use bounded exponential backoff for reads. Do not blindly retry task creation, generation, or key mutations, to avoid duplicate billing or execution.

## Constraints

This page describes the base protocol. Use the selected model quick start for supported fields, enums, limits and asynchronous behavior. Replace YOUR_MODEL. Form initial values are not upstream defaults.

## Documentation source

Definition version: 1

Reviewed: 2026-11-02

Source: https://api.tu-zi.com/en/docs/api/reference-relay-anthropic

Related protocol guide: https://api.tu-zi.com/docs/api/anthropic

This export contains documentation and examples only, without real credentials, account data or user requests.