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This capability is in beta. Behavior can change before general availability.
At the end of this page, your voice agent can call tools during a call, before it starts or after it ends, and can search your knowledge bases. A tool runs while the caller waits, so this page also covers what the caller hears meanwhile.

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Before you start

Before you start, sign in to the dashboard and select the organization you want to work in.
  • A voice agent. See Create a voice agent.
  • Your role includes Build chat agents, voice agents, knowledge bases & tools.
  • For integration actions, a connected toolkit or a CodeKit toolkit. See Connect a toolkit.

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Add a tool

1

Open the voice agent and expand Tools in the settings rail

The Tools section lists the tools this voice agent can use.
2

Select Add tool and choose a tool

Built-in tools and Integrations are listed separately.
3

Enter a Callable name and describe When should the agent use it?

The model reads this description to decide when to call the tool. Use a snake_case name.
4

Set the tool's fields, then save

The tool shows in the Tools list with its kind, such as built-in, custom or code.
In a conversation flow, a Tool or Code flow node runs one tool on entry, and a Subagent flow node carries its own tools. See Add flow nodes. Large tool lists slow responses and make the voice agent less accurate at choosing a tool.

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Built-in tools

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Call your own API

A Custom Function sends an HTTP request. Each input takes its value from one of four sources: Conversation variable, Fixed value, Agent fills, or Prior result. With Agent fills, describe in What this value means what the model must provide. Test request sends the request with sample values and shows the Request to send, the Response body, and What the agent sees. Save the tool changes before you test.

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Use an integration action

Select Integrations in Add tool. Choose a connected account or a CodeKit toolkit, then the actions this voice agent can use. The Defaults for selected actions apply to every action you include. Select Override for this action to change one action. Removing an integration from the voice agent keeps the connected account in Tools.

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Decide when a tool runs

Run sets the stage of the call: Tools before and after the call run without the caller, so they ask for no confirmation and say nothing. A single prompt voice agent shows these stages on its Workflow page. A conversation flow keeps Pre-call tools on Begin and Post-call tools in Global Settings → After the call. Where is it available? limits a tool to some conversation states. Everywhere makes it available in every state.

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Add safeguards

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Set what the caller hears

Say something while it runs sets the line the voice agent says while the tool runs:
  • None adds no line.
  • Prompt gives the voice agent an instruction, and it says one short line in its own words.
  • Static says your exact sentence after variables are filled.
The Subtle typing sound while it runs setting plays a quiet sound while the caller waits. With Wait for the result, the voice agent waits for the tool before it speaks.

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Save results as variables

Result fields save parts of a tool’s result as variables that later steps can read. A tool that declares no output fields cannot save results as variables.

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Attach a knowledge base

1

Expand Knowledge base in the settings rail and select Add knowledge base

The list shows the knowledge bases in your organization.
2

Choose a knowledge base and select Done

The voice agent can now search its indexed passages during a call.
3

Optional: write a Knowledge instruction

Tell the voice agent how to use retrieved passages, such as “Answer only from the retrieved passages”.
The Passages per lookup setting sets how many passages each search returns. The Minimum similarity setting drops passages below that score. In a conversation flow, Knowledge on a flow node attaches a knowledge base to that flow node only.

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Verify

Open the test panel and select Text chat. Ask something that needs the tool or the knowledge base. Tool calls and knowledge searches show in the transcript. Tools that change data must be mocked in tests. See Test and publish a voice agent.