> ## Documentation Index
> Fetch the complete documentation index at: https://openrouter-d02e98a0-mintlify-a46887cf.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# CustomToolCallItem - Go SDK

> CustomToolCallItem type definition

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

A call to a custom (freeform-grammar) tool created by the model — distinct from `function_call`. Used for tools like Codex CLI's `apply_patch` whose payload is opaque text rather than JSON arguments.

## Fields

| Field       | Type                                                                                             | Required             | Description                                                                                     |
| ----------- | ------------------------------------------------------------------------------------------------ | -------------------- | ----------------------------------------------------------------------------------------------- |
| `CallID`    | `string`                                                                                         | :heavy\_check\_mark: | N/A                                                                                             |
| `ID`        | `*string`                                                                                        | :heavy\_minus\_sign: | N/A                                                                                             |
| `Input`     | `string`                                                                                         | :heavy\_check\_mark: | N/A                                                                                             |
| `Name`      | `string`                                                                                         | :heavy\_check\_mark: | N/A                                                                                             |
| `Namespace` | `*string`                                                                                        | :heavy\_minus\_sign: | Namespace qualifier for tools registered as part of a namespace tool group (e.g. an MCP server) |
| `Type`      | [components.CustomToolCallItemType](/client-sdks/go/api-reference/models/customtoolcallitemtype) | :heavy\_check\_mark: | N/A                                                                                             |