---
title: "CustomToolCallOutputItem"
---

The output from a custom (freeform-grammar) tool call execution. Mirrors `function_call_output` but is matched to a `custom_tool_call` rather than a `function_call`.


## Fields

| Field                                                                                                                            | Type                                                                                                                             | Required                                                                                                                         | Description                                                                                                                      |
| -------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------- |
| `call_id`                                                                                                                        | *str*                                                                                                                            | :heavy_check_mark:                                                                                                               | N/A                                                                                                                              |
| `id`                                                                                                                             | *Optional[str]*                                                                                                                  | :heavy_minus_sign:                                                                                                               | N/A                                                                                                                              |
| `output`                                                                                                                         | [components.CustomToolCallOutputItemOutputUnion2](../components/customtoolcalloutputitemoutputunion2.mdx)                         | :heavy_check_mark:                                                                                                               | N/A                                                                                                                              |
| `type`                                                                                                                           | [components.CustomToolCallOutputItemTypeCustomToolCallOutput](../components/customtoolcalloutputitemtypecustomtoolcalloutput.mdx) | :heavy_check_mark:                                                                                                               | N/A                                                                                                                              |