### Authentication

**X-Hume-Api-Key**  
API Key authentication via header

### Path parameters

- **id** `string` Required `format: "uuid"`  
  Identifier for a Tool. Formatted as a UUID.

- **version** `integer` Required  
  Version number for a Tool.  
  Tools, Configs, Custom Voices, and Prompts are versioned. This versioning system supports iterative development, allowing you to progressively refine tools and revert to previous versions if needed.  
  Version numbers are integer values representing different iterations of the Tool. Each update to the Tool increments its version number.

### Request

This endpoint expects an object.

- **version_description** `string` or null Optional  
  An optional description of the Tool version.

### Response

**Success**

- **created_on** `long`  
  The timestamp when the first version of this tool was created.

- **id** `string`  
  Identifier for a Tool. Formatted as a UUID.

- **modified_on** `long`  
  The timestamp when this version of the tool was created.

- **name** `string`  
  Name of the built-in tool to use. Hume supports the following built-in tools:
  - **web_search:** enables EVI to search the web for up-to-date information when applicable.
  - **hang_up:** closes the WebSocket connection when appropriate (e.g., after detecting a farewell in the conversation).

For more information, see our guide on [using built-in tools](https://dev.hume.ai/docs/speech-to-speech-evi/features/tool-use#using-built-in-tools).

- **parameters** `string`  
  Stringified JSON defining the parameters used by this version of the Tool.  
  These parameters define the inputs needed for the Tool's execution, including the expected data type and description for each input field. Structured as a stringified JSON schema, this format ensures the Tool receives data in the expected format.

- **tool_type** `enum`  
  Allowed values: BUILTIN FUNCTION

- **version** `integer`  
  Version number for a Tool. Version numbers should be integers. The combination of configId and version number is unique.

- **version_type** `enum`  
  Allowed values: FIXED LATEST

- **description** `string` or null  
  An optional description of what the Tool does, used by the supplemental LLM to choose when and how to call the function.

- **fallback_content** `string` or null  
  Optional text passed to the supplemental LLM in place of the tool call result. The LLM then uses this text to generate a response back to the user, ensuring continuity in the conversation if the Tool errors.

- **version_description** `string` or null  
  An optional description of the Tool version.