Hi VAPI Support, We are experiencing an issue with warm transfer summaries failing, causing all transfers to fall back to blind transfers. Call ID: 019d7934-d8c3-766c-b63f-9c71ccfbe32b Issue: The summary plan is sending an empty messages array to the LLM during transfer. In the logs, the Anthropic request shows "messages": [] with no transcript content, which causes the summary generation to fail entirely with the error: "All model completion attempts failed. Last error: TypeError: Cannot read properties of undefined (reading '0')" The transfer tool is configured with mode: warm-transfer-wait-for-operator-to-speak-first-and-then-say-summary and useAssistantLlm: false, but the {{transcript}} variable does not appear to be populating into the summary request before it is sent to the model. Please investigate why the transcript is not being injected into the summary plan messages. Thank you.

Hi there, Thanks for flagging this — we were able to identify the issue. Your

summaryPlan

configuration currently includes two messages with the role

"system"

. When this gets converted into OpenAI-compatible format for Anthropic, those system messages are being omitted, which results in an empty

messages

array being sent to the model. To resolve this, please: • Replace both

"system"

role messages with

"user"

• Insert the

{{transcript}}

variable directly into the message content This will ensure the transcript is properly passed into the model and allow the summary to generate as expected. Let us know if you run into any issues after making this change. Best, VAPI Support