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In a conversation flow, integration tools run through a function node: the node fires the tool on entry, and the flow transitions on the result. Retell handles the provider’s API and auth, so there’s no server of your own in between. For single- and multi-prompt agents, add the same tools from the Functions section instead; see integration tools for prompt agents. See the integrations overview for the providers Retell connects to, what each one’s tools do, and how to connect them. Subagent nodes can use integration tools too, alongside their other tool types. Integration tools can also run outside the conversation, before it starts or after it ends; see agent workflow.

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Add an integration tool to a flow

1

Connect the provider

Connect it once on the dashboard’s Integrations page — a workspace-level step covered in the integrations overview.
2

Add the tool from the function menu

In the flow, add a function; connected providers’ tools appear in the menu grouped by provider. You can also pick Add integration in the menu to connect a new provider without leaving the flow.
Add-function dialog with the Microsoft Dynamics 365 integration menu open. Create Task is hovered and its description is visible; the Add button is outlined in blue.

Adding a Microsoft Dynamics 365 tool to a conversation flow's function node.

3

Select it inside a function node

Pick the tool in the node, as with any function. Configuration works the same as for prompt agents: inputs are fixed values or filled from the conversation, response fields map to dynamic variables, and you can test the tool with a live request before the first call.

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Branch on the result

The function node considers the tool’s result for transition timing (see when transitions happen), so your transition conditions can branch on what came back: one edge for “contact found”, another for “no match”, each leading to a different conversation node. Each tool call times out after 3 to 14 seconds, depending on the provider and tool (as of August 2026). On timeout or error the flow still transitions, so give errors their own edge rather than letting them fall through a success path. To route on execution failure, open Function fields → Output in the tool’s configuration and name the Success status variable contact_lookup_status. Select Wait for completion in the function node, then use conditions such as {{contact_lookup_status}} == "success" and {{contact_lookup_status}} == "failure". Check response fields separately to distinguish a matching contact from an empty result. See configure execution status for the output settings and skipped-tool behavior.