Vapi Calls - Agent Instructions
Use this skill to perform any task that requires voice interaction over the phone.
Configuration & Network Requirements
⚠️ IMPORTANT: This skill requires your machine to be reachable from the internet to receive real-time call updates.
1. Environment Variables
Configure these in your OpenClaw config.json (or Gateway env):
VAPI_API_KEY: Your Vapi Private API Key.VAPI_ASSISTANT_ID: The ID of the Vapi Assistant to use as a base.VAPI_PHONE_NUMBER_ID: The ID of the Vapi Phone Number.WEBHOOK_BASE_URL: Crucial. The public HTTPS URL where this agent is reachable (e.g.,https://my-claw.comorhttps://xyz.ngrok-free.app). Do not include a trailing slash.WEBHOOK_PORT(Optional): The local port to listen on (Default:4430).VAPI_LLM_PROVIDER: (Optional) Provider for Custom Mode (Default:openai).VAPI_LLM_MODEL: (Optional) Model for Custom Mode (Default:gpt-4o-mini).
2. Connectivity Setup
You must expose the WEBHOOK_PORT (default 4430) to the internet.
Option A: Cloudflare Tunnel (Recommended)
cloudflared tunnel --url http://localhost:4430
Option B: Ngrok
ngrok http 4430
Set WEBHOOK_BASE_URL to the generated URL (e.g., https://random-name.trycloudflare.com).
Usage
Custom Mission (Dynamic)
Provide a specific system_prompt. The system will automatically use GPT-4o Mini and enable the endCall tool. The AI will be able to hang up autonomously.
Native Agent (Static)
Pass "DEFAULT" for first_message, system_prompt, and end_message. The system will use the exact configuration (Model, Voice, Prompt) defined in the Vapi Dashboard.
Troubleshooting
- Call hangs / No report: Check if
WEBHOOK_BASE_URLis reachable from the internet. The Python script spins up a temporary server onWEBHOOK_PORTonly during the call. - API 400 Error: Check your
VAPI_PHONE_NUMBER_IDandVAPI_ASSISTANT_ID.