Creates a **Tool** that can be added to an [EVI configuration](https://dev.hume.ai/reference/speech-to-speech-evi/configs/create-config).

Refer to our [tool use](https://dev.hume.ai/docs/speech-to-speech-evi/features/tool-use#function-calling) guide for comprehensive instructions on defining and integrating tools into EVI.

### Authentication

X-Hume-Api-Keystring

API Key authentication via header

### Request

This endpoint expects an object.

- **name** string Required  
  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 Required  
  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.
- **description** string or null Optional  
  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  
  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 Optional  
  An optional description of the Tool version.

### Response

- **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.