> ## Documentation Index
> Fetch the complete documentation index at: https://openrouter-d02e98a0-mintlify-5b6e02fd.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# CustomToolCallOutputItem - Go SDK

> CustomToolCallOutputItem type definition

<Warning>
  The Go SDK and docs are currently in beta.
  Report issues on [GitHub](https://github.com/OpenRouterTeam/go-sdk/issues).
</Warning>

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 |
| -------- | ---------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------- | ----------- |
| `CallID` | `string`                                                                                                                                             | :heavy\_check\_mark: | N/A         |
| `ID`     | `*string`                                                                                                                                            | :heavy\_minus\_sign: | N/A         |
| `Output` | [components.CustomToolCallOutputItemOutputUnion2](/client-sdks/go/api-reference/models/customtoolcalloutputitemoutputunion2)                         | :heavy\_check\_mark: | N/A         |
| `Type`   | [components.CustomToolCallOutputItemTypeCustomToolCallOutput](/client-sdks/go/api-reference/models/customtoolcalloutputitemtypecustomtoolcalloutput) | :heavy\_check\_mark: | N/A         |