---
title: "ChatStreamToolCall"
---

Tool call delta for streaming responses


## Fields

| Field                                                                                          | Type                                                                                           | Required                                                                                       | Description                                                                                    | Example                                                                                        |
| ---------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------- |
| `function`                                                                                     | [Optional[components.ChatStreamToolCallFunction]](../components/chatstreamtoolcallfunction.mdx) | :heavy_minus_sign:                                                                             | Function call details                                                                          |                                                                                                |
| `id`                                                                                           | *Optional[str]*                                                                                | :heavy_minus_sign:                                                                             | Tool call identifier                                                                           | call_abc123                                                                                    |
| `index`                                                                                        | *int*                                                                                          | :heavy_check_mark:                                                                             | Tool call index in the array                                                                   | 0                                                                                              |
| `type`                                                                                         | [Optional[components.ChatStreamToolCallType]](../components/chatstreamtoolcalltype.mdx)         | :heavy_minus_sign:                                                                             | Tool call type                                                                                 | function                                                                                       |