VAPI•7mo ago

Prompt injection on web platform

I was not able to find this, and so I would love help with this. It appears that setting up prompt injection into the system prompt for the beginning of a call in {{}} format (other than system-provided ones like {{ date }} and {{ time }}) is tied into the phone number, not the assistant. This is a little annoying as when testing web calls, it is not injected then. Is there an alternative recommended, and are you intending on allowing this to be tied to the assistant also at some point? Apologies if this is documented, I was not able to find it.

Vapi Support BotAPP•6/6/25, 3:06 PM

Thank you for your question! Based on the documentation, dynamic variable injection (using {{}}{{}} syntax) is supported for phone calls via API, but there is no clear support or alternative documented for web calls, nor mention of future plans to tie this to the assistant itself.

To better assist you, could you clarify if your main goal is to have dynamic variables automatically injected for web calls without needing to set them programmatically each time?

Sources:

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

few-sapphireOP•6/6/25, 6:12 PM

Yes that is correct. I would like a server to be able to be set so that it can get the dynamic variables immediately when starting a call, whether from the web or from a phone call

KyleAPP•6/7/25, 12:24 AM

Hey Noha Vandal, check out this documentation on how to use dynamic variables with the assistant and how to customize calls based on user data right before a call connects with the customer.

https://docs.vapi.ai/assistants/personalization

few-sapphireOP•6/9/25, 1:37 AM

Thank you~!

few-sapphireOP•6/9/25, 1:38 AM

But a question about that. That still only seems to work with PHONE NUMBER calling, and I am wondering if there is a way to do that same thing (of dynamic injection), but for web use. (when not using an actual phone number), s that does not seem to support that?

KyleAPP•6/9/25, 9:22 PM

Hey Noah, for web calls you can pass the transient assistant config directly you don't need to use assistant overrides.

Prompt injection on web platform

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