VAPI•4mo ago

Handling calls for the returning users

Greetings,

I need some help with returning customers. I'm trying to load a digest of their previous conversation at the start of a new call.

Right now, I have two assistants- one for new users and one for returning ones. They're supposed to invoke a tool to load the conversation digest from my backend.

The problem is the tool only gets triggered if the user explicitly asks for it. I need it to fire automatically right when the call starts.

Ideally, I'd like to use a single assistant and just swap out the system context. Is that even possible? I checked the docs for creating assistants but couldn't find a way to automatically trigger a tool at the beginning of the call.

What's the best way to handle this? Is there an on-start event I can use to trigger a tool, or am I thinking about this all wrong? Should I be using workflows for this instead?

Any help would be great. Thanks.

KyleAPP•9/10/25, 3:05 PM

Hi yarcat,

To automatically trigger a tool at the start of a call, you can include it in the firstMessagefirstMessage configuration of your assistant or use a custom function to call your backend upon call initiation.

Here’s a basic method to achieve this:

Use the firstMessageModefirstMessageMode: Set firstMessageModefirstMessageMode to "assistant-speaks-first""assistant-speaks-first".
Invoke the Tool Automatically: Modify the firstMessagefirstMessage content to include the logic to call the tool. This could require configuring a system prompt that contains instructions for the assistant to call the backend tool immediately.

For a single assistant setup, configure the assistant on your server to recognize returning users:

{
  "assistant": {
    ...
    "firstMessage": "Welcome back, {{userName}}. Let me check the latest updates on our previous conversation.",
    "firstMessageMode": "assistant-speaks-first"
    ...
  },
  "tools": [
    {
      "type": "apiRequest",
      "name": "loadConversationDigest",
      "url": "https://api.your-backend.com/conversation-digest",
      "method": "GET",
      "parameters": {
        "userId": "{{userId}}"
      }
    }
  ]
}

{
  "assistant": {
    ...
    "firstMessage": "Welcome back, {{userName}}. Let me check the latest updates on our previous conversation.",
    "firstMessageMode": "assistant-speaks-first"
    ...
  },
  "tools": [
    {
      "type": "apiRequest",
      "name": "loadConversationDigest",
      "url": "https://api.your-backend.com/conversation-digest",
      "method": "GET",
      "parameters": {
        "userId": "{{userId}}"
      }
    }
  ]
}

Replace placeholders like {{userName}}{{userName}} and {{userId}}{{userId}} with the appropriate dynamic variables or session data. This should help in fetching the conversation digest automatically as soon as the call starts, without needing a manual user prompt.

If this doesn’t resolve the issue, please let us know and we’ll be happy to step in and assist further.

brilliant-orange•9/10/25, 5:31 PM

I have this exact same agentd for a dealership. For rrturning customers, you have to explicitly say something like "Refer to this conversation for customer context" then your custom variable for that.

For names, I use custom variables too.

KyleAPP•9/11/25, 10:58 PM

Hello,

Thanks for getting back.

You're right! When handling returning customers and personalizing conversations, you need to:

For customer context/history:
Add an explicit instruction in your system prompt like "Refer to this conversation for customer context: {{customerContext}}"
Set the context value through `variableValues` when starting the call
For customer names:
Use the variable syntax: {{customerName}}{{customerName}} (or your preferred variable name)
Provide the value through assistantOverridesassistantOverrides when making the call:

{  "assistantOverrides": {    "variableValues": {      "customerContext": "Previous conversation about billing issue on Sept 1",      "customerName": "John"    }  }}

{  "assistantOverrides": {    "variableValues": {      "customerContext": "Previous conversation about billing issue on Sept 1",      "customerName": "John"    }  }}

Remember that variables must be set when starting the call - they cannot be set in the dashboard directly

Handling calls for the returning users

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