How can I make parameter of a tool become optional LiveKit Community #ask-ai

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How can I make parameter of a tool become optional...

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able-airline-55422

12/15/2025, 5:08 AM

How can I make parameter of a tool become optional?

tall-airline-16756

12/15/2025, 5:08 AM

Thanks for reaching out, Rod. I'm an AI assistant and I'm here to help. Give me a moment while I research this topic.

tall-airline-16756

12/15/2025, 5:09 AM

You're asking how to make a tool parameter optional — here's a concise way to do that when defining tool parameters with Zod in LiveKit Agents. 1. Mark the field as optional in the Zod schema using `.optional()`:

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parameters: z.object({
  location: z.string().describe('The location to get weather for'),
  unit: z.enum(['celsius','fahrenheit']).optional(), // optional parameter
})

1. Provide a default inside

execute

so your code has a fallback when the parameter is omitted:

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execute: async ({ location, unit = 'celsius' }) => {
  // unit will be 'celsius' if omitted
}

That’s all — the parameter can be omitted when invoking the tool, and your

execute

handler receives either the provided value or the default. Would you like an example for a different parameter type or validation rule? Sources: Agents (Node.js) | livekit/livekit_composite | DeepWiki

able-airline-55422

12/15/2025, 5:09 AM

I am using python

tall-airline-16756

12/15/2025, 5:10 AM

Thanks — since you’re using Python, make the parameter optional by giving it a default value in your tool function. The

@function_tool

decorator will treat parameters with defaults as optional. Example:

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from livekit.agents import function_tool

@function_tool()
async def get_weather(
    location: str,            # required
    unit: str = "celsius"     # optional with default
) -> str:
    return f"Weather in {location}: 20 degrees {unit}"

Do you want an example that validates allowed values for

unit

(e.g., only "celsius" or "fahrenheit") or one that uses

Optional[...]

typing? Sources: Tool definition and use | LiveKit docs

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