> For the complete documentation index, see [llms.txt](https://docs.voiceb.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.voiceb.ai/tools-connect-your-agent-to-external-actions/tool-execution-modes.md).

# Tool execution modes

Choose whether the agent waits for a tool's response (Immediate) or keeps the conversation flowing while the action runs in the background (Async).

## Tool execution modes

Tools are actions the agent can execute during a call — for example, looking up or saving information in one of your systems through a webhook.

Each tool runs in one of two execution modes:

| Mode                    | What it does                                                                     |
| ----------------------- | -------------------------------------------------------------------------------- |
| **Immediate** (default) | The agent waits for the tool's response before continuing the conversation.      |
| **Async**               | The agent triggers the action and keeps talking, without waiting for a response. |

### When to use Async

Choose Async for actions whose result the agent doesn't need to say out loud during the call. For example:

* Registering an event or updating a record in your CRM.
* Triggering an internal notification.

Running these in the background avoids silences and unnatural pauses while the agent waits for an external system to respond.

Keep **Immediate** whenever the agent needs the result to continue the conversation — for example, checking an order status or availability that the agent has to read back to the lead.

<figure><img src="https://2950912279-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FggIr2RvhGm49D4vbjurT%2Fuploads%2FitgWBP94m2o8Zrp6CbG5%2FScreenshot%202026-08-18%20at%2010.42.45.png?alt=media&amp;token=ef22d05c-a2b4-4f5a-abab-d0e193334dad" alt=""><figcaption></figcaption></figure>

### Setting it up

1. Go to **Tools** in your organization menu.
2. Create a new tool, or edit an existing one.
3. In the tool form, set the **Execution mode** field to **Immediate** or **Async**.
4. Save. The mode is stored together with the rest of the tool's configuration (webhook, parameters, variables…).

### Good to know

* Async mode is only available for agents that use **ElevenLabs** as their voice provider. It is **not supported on Bland**.
* A tool set to Async **cannot be assigned to an agent running on Bland** — the interface will warn you when you select this mode.


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