Transfer Call Tool “Couldn’t get assistant” Error Vapi AI #support

Transfer Call Tool “Couldn’t get assistant” Error

kker4m

07/11/2025, 2:27 PM

I’ve created a test “Transfer Call” tool between two assistants I set up, intending for one assistant to transfer the call to the other. However, when I trigger the transfer, I receive a couldn't get assistant error. When I remove the tool from usage, everything works fine again — the issue disappears entirely. Looks like the transfer tool is causing the assistant resolution to fail. Let me know if logs or assistant IDs are needed.

Chiranjeet Mishra

07/13/2025, 12:05 AM

Hey kker4m, Thank you for reaching out. Please note that our team does not operate over the weekend. We'll be back in the office on Monday and will dive straight into your issue then to determine the best way forward.

Chiranjeet Mishra

07/15/2025, 4:50 PM

Here are a few steps to troubleshoot and resolve this problem: 1. **Assistant Configuration**: - Check that each assistant has only one

transferCall

tool configured. Multiple tools of the same type can cause configuration errors. Refer to the [Default Tools documentation](https://docs.vapi.ai/tools/default-tools) for ensuring correct configuration. 2. **Assistant Destination Configuration**: - Ensure that the destination assistant's ID or name is correctly specified in the

assistantDestinations

array. The assistant name or ID should match exactly with what is registered in the system. For details, you can review the [Silent Transfers documentation](https://docs.vapi.ai/squads/silent-transfers). 3. **Logging and Validation**: - If the error persists, check the logs to ensure there are no schema validation errors or other configuration warnings when you attempt the transfer. This can indicate missing or incorrect values in your

transferCall

tool configuration. 4. **Test with Minimal Configuration**: - Temporarily simplify your setup to isolate the problem. Use a minimal transfer configuration to test the basic functionality and then layer additional configurations step by step.

MedB

07/31/2025, 1:57 PM

I'm having a very similar issue. I have AssistantA and AssistantB. When I put the following into the prompt in ASSISTANTA (the source assistant) " trigger the 'transferCall tool with 'AssistantB'" it worked despite not having the actual tool enabled in AssistantA. When I DID enable the tool it had the same issue of saying assistant could not be found. I should also note I also had AssistantA leading to AssistantB in a squad. I dont have the prompts written in the squad interface, only in the assistant interface. So a bunch of questions: 1. Why do we even need the tool if the just instructing the agent to transfer to a different agent in the prompt works? 2. Why do even need squads in the first place if you can transfer from agent to agent. 3. Is there something about the configuration I described above which jumps out at you as problematic 4. Even when the transfer works as described above, I CANNOT get it to do it silently. How can I do this? I have the destination assistant (AssistantB) configured with the first message empty and "assistant speaks first with model generated message) set. I've even tried instructing in the prompt to do it silently and don't use words like transfer etc. Yet it keeps saying outloud something to the effect of "transferring you now". Any help you could give are much appreciated!

MedB

07/31/2025, 4:08 PM

One additional piece here. I tried an assistant to assistant transfer WITHOUT a squad. I ensured that neither of the assistants were in any squads or in any other tools. I used the transfer call tool to build it. I put the destination assistant so that it matches the assistant name exactly (The name in question is ELLIE_B). I added the tool to the source assistant (JAMIEB) and invoked the tool correctly with the following: trigger the transferCall tool with 'ELLIE_B' Assistant. Tried over and over and got a red error box in the bottom right hand corner saying "Invalid Destination. "ELLIE_B" does not exist. I even tried redoing the tool and the prompt with the assistant ID instead of name. Nothing worked.

Chiranjeet Mishra

08/04/2025, 9:48 AM

Hey, let me check with our team and get back to you with an update.

MedB

08/07/2025, 12:29 PM

any updates here?

Chiranjeet Mishra

08/09/2025, 2:45 PM

Hey! To help track down this issue, could you share: - The call ID This would really help us figure out what went wrong!

Daniel F.

08/14/2025, 3:58 PM

I am experiencing the same issue. Any news on whats wrong with the transferCall tool with Assistant as a destination? @Vapi

Chiranjeet Mishra

08/16/2025, 7:29 AM

If you would like to perform an assistant to assistant transfer, we highly recommend using squads instead of using the transfer tool. There are some issues with the transferCall tool when defining an assistant as the destination and in the future there will be a release that addresses this issue, but there is no ETA on that release.

Daniel F.

08/16/2025, 2:01 PM

Thanks for addressing the question. It can be confusing leaving broken features accessible in the dashboard. Its been quite a long time since this transferCall tool destination to assistant is there and not working. Would be a good thing to remove it until its working.

Chiranjeet Mishra

08/18/2025, 3:18 AM

We will discuss this with the team and see if there's something that could be done about that.

Previous Next