> ## Documentation Index
> Fetch the complete documentation index at: https://docs.anyfast.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Claude 3.7 Sonnet Thinking

> Anthropic's Claude 3.7 Sonnet with extended thinking enabled. Deep reasoning for math, coding, and complex analysis.

Claude 3.7 Sonnet Thinking is the extended thinking variant of Claude 3.7 Sonnet, available through Anyfast via an OpenAI-compatible interface. With extended thinking enabled by default, the model performs step-by-step internal reasoning before generating a response, delivering significantly improved accuracy on complex tasks.

## Key capabilities

* **OpenAI-compatible** — Works as a drop-in replacement with the OpenAI SDK
* **Extended thinking** — Step-by-step internal reasoning enabled by default
* **Deep reasoning** — Excels at math, logic, and multi-step problem solving
* **Long context** — Handles large documents and multi-turn conversations
* **Streaming** — Supports real-time token streaming via SSE

## Quick example

<CodeGroup>
  ```bash cURL theme={null}
  curl https://www.anyfast.ai/v1/messages \
    -H "Authorization: Bearer YOUR_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{
      "model": "claude-3-7-sonnet-20250219-thinking",
      "messages": [
        { "role": "user", "content": "Solve step by step: If a train travels 120 km in 2 hours, then slows down and travels 80 km in 3 hours, what is the average speed for the entire trip?" }
      ]
    }'
  ```

  ```python Python theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="YOUR_API_KEY",
      base_url="https://www.anyfast.ai/v1"
  )

  response = client.chat.completions.create(
      model="claude-3-7-sonnet-20250219-thinking",
      messages=[
          {"role": "user", "content": "Solve step by step: If a train travels 120 km in 2 hours, then slows down and travels 80 km in 3 hours, what is the average speed for the entire trip?"}
      ]
  )

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

  ```python Streaming theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="YOUR_API_KEY",
      base_url="https://www.anyfast.ai/v1"
  )

  stream = client.chat.completions.create(
      model="claude-3-7-sonnet-20250219-thinking",
      messages=[
          {"role": "user", "content": "Write a proof that there are infinitely many prime numbers."}
      ],
      stream=True
  )

  for chunk in stream:
      print(chunk.choices[0].delta.content or "", end="")
  ```
</CodeGroup>

## Parameters

| Parameter     | Type           | Required | Description                                   |
| ------------- | -------------- | -------- | --------------------------------------------- |
| `model`       | string         | Yes      | Must be `claude-3-7-sonnet-20250219-thinking` |
| `messages`    | array          | Yes      | List of `{ role, content }` objects           |
| `max_tokens`  | integer        | No       | Maximum tokens to generate                    |
| `temperature` | float          | No       | `0`–`2`. Controls randomness. Default: `1`    |
| `stream`      | boolean        | No       | Enable SSE streaming. Default: `false`        |
| `top_p`       | float          | No       | Nucleus sampling threshold. Default: `1`      |
| `stop`        | string / array | No       | Sequences that stop generation                |

<Card title="API Reference" icon="code" href="/api-reference/model-api/anthropic/claude-3-7-sonnet-20250219-thinking">
  View the interactive API playground for Claude 3.7 Sonnet Thinking.
</Card>

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