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

# Claude Token Counting

> POST /v1/messages/count_tokens estimate the input token count for a Claude Messages request

> Дата обновления: 2026-06-06

# Claude Token Counting

```
POST /v1/messages/count_tokens
```

Use this endpoint to estimate input token usage before you send the real `POST /v1/messages` request. It is useful for Claude CLI, Claude Code, budget checks, and context-trimming logic.

## Authentication

The recommended headers follow Anthropic-style requests:

```http theme={null}
x-api-key: YOUR_API_KEY
anthropic-version: 2023-06-01
```

Standard Bearer authentication also works, but Anthropic ecosystem clients usually send the headers above.

## Request Body

The body follows the Claude Messages shape. The smallest practical request usually includes:

* `model`
* `messages`

If your request also includes `system`, `tools`, tool results, or text content, those are included in the estimate too.

## Request Example

<CodeGroup>
  ```bash cURL theme={null}
  curl https://api.crazyrouter.com/v1/messages/count_tokens   -H "Content-Type: application/json"   -H "x-api-key: YOUR_API_KEY"   -H "anthropic-version: 2023-06-01"   -d '{
      "model": "claude-opus-4-8",
      "messages": [
        {"role": "user", "content": "hello"}
      ]
    }'
  ```

  ```python Python theme={null}
  import requests

  resp = requests.post(
      "https://api.crazyrouter.com/v1/messages/count_tokens",
      headers={
          "x-api-key": "YOUR_API_KEY",
          "anthropic-version": "2023-06-01",
          "Content-Type": "application/json",
      },
      json={
          "model": "claude-opus-4-8",
          "messages": [
              {"role": "user", "content": "hello"}
          ],
      },
  )

  print(resp.json())
  ```
</CodeGroup>

## Response Example

```json theme={null}
{
  "input_tokens": 4
}
```

## Response Fields

| Field          | Type    | Description                                                                         |
| -------------- | ------- | ----------------------------------------------------------------------------------- |
| `input_tokens` | integer | Estimated input tokens for the text portion of the request                          |
| `warning`      | string  | Optional warning; may appear when images or files were not included in the estimate |

## Current Limits

The current implementation mainly estimates:

* `system`
* text content in `messages`
* text and JSON content in tool definitions and tool results

<Warning>
  If the request contains images or files, those image/file tokens are not included in `input_tokens`. In that case the response may include a `warning`, and real billing can be higher than this estimate.
</Warning>

<Note>
  This endpoint returns an estimate, not a final billing record. Actual usage is determined by the real model call.
</Note>