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.com or https://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_URL is reachable from the internet. The Python script spins up a temporary server on WEBHOOK_PORT only during the call.
• API 400 Error: Check your VAPI_PHONE_NUMBER_ID and VAPI_ASSISTANT_ID.