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SKILL.md
npx skills add vapiai/skills --skill setup-webhook
Configure Vapi server URLs and webhooks to receive real-time call events, transcripts, tool calls, and end-of-call reports. Use when setting up webhook endpoints, building tool servers, or integrating Vapi events into your application.
npx skills add vapiai/skills --skill setup-webhook
Configure server URLs to receive real-time events from Vapi during calls — transcripts, tool calls, status changes, and end-of-call reports.
Setup: Ensure
VAPI_API_KEYis set. See thesetup-api-keyskill if needed.
Vapi uses "Server URLs" (webhooks) to communicate with your application. Unlike traditional one-way webhooks, Vapi server URLs support bidirectional communication — your server can respond with data that affects the call.
Create the optional credentialId in Dashboard > Custom Credentials. Omit it only for a deliberately public endpoint.
Phone-number updates also use a server object with url and optional credentialId. When updating through the API, first retrieve the number and preserve its existing provider discriminator in the PATCH body. The dashboard is the safest choice when the provider is unknown.
Set a default server URL in the Vapi Dashboard under Settings > Server URL.
Priority order: Tool server URL > Assistant server URL > Phone Number server URL > Organization server URL.
| Event | Description | Expects Response? |
|---|---|---|
assistant-request | Request for dynamic assistant config | Yes — return assistant config |
tool-calls | Assistant is calling a tool | Yes — return tool results |
status-update | Call status changed | No |
transcript | Real-time transcript update | No |
end-of-call-report | Call completed with summary | No |
hang | Assistant failed to respond | No |
speech-update | Speech activity detected | No |
Use a Vapi Custom Credential and place its ID in server.credentialId. Vapi supports Bearer Token, OAuth 2.0 client credentials, and HMAC credentials. Verify requests according to the credential you configured; HMAC header names, algorithms, timestamps, and payload formats are configurable, so do not assume a fixed x-vapi-signature format.
For a bearer credential, compare the incoming Authorization: Bearer <token> value with the token stored securely by your server. Never put the secret itself in an assistant or phone-number payload.
Use the Vapi CLI with a public tunnel. The CLI forwards from port 4242 to your app, but it does not create the public URL itself:
Set the Vapi server URL to the public ngrok URL. To skip the CLI and tunnel directly to the Express or Flask server instead:
The end-of-call-report event includes:
| Field | Description |
|---|---|
call | Full call object with metadata |
endedReason | Why the call ended |
artifact | Recording, transcript, messages, and other enabled artifacts |
analysis | Configured summaries, structured data, and success evaluation |
cost | Total call cost |
startedAt / endedAt | Call timing, when included |
Vapi provides a documentation MCP server that gives compatible AI agents access to the Vapi knowledge base. Use its documentation search for advanced configuration, troubleshooting, SDK details, and anything beyond this skill.
To add the Vapi documentation MCP server manually in Claude Code, run:
See the Vapi MCP integration guide for setup instructions across supported agents.
import express from "express";
const app = express();
app.use(express.json());
app.post("/vapi/webhook", (req, res) => {
const { message } = req.body;
switch (message.type) {
case "assistant-request":
// Dynamically configure the assistant based on the caller
res.json({
assistant: {
name: "Dynamic Assistant",
firstMessage: `Hello ${message.call.customer?.name || "there"}!`,
model: {
provider: "openai",
model: "gpt-4.1",
messages: [
{ role: "system", content: "You are a helpful assistant." },
],
},
voice: { provider: "vapi", voiceId: "Elliot", version: 2 },
transcriber: { provider: "deepgram", model: "nova-3", language: "en" },
},
});
break;
case "tool-calls":
// Handle tool calls from the assistant
const results = (message.toolCallList || []).map((toolCall: any) => ({
toolCallId: toolCall.id,
result: handleToolCall(
toolCall.name,
toolCall.parameters || toolCall.arguments
),
}));
res.json({ results });
break;
case "end-of-call-report":
// Process the call report
console.log("Call ended:", {
callId: message.call.id,
endedReason: message.endedReason,
cost: message.cost,
analysis: message.analysis,
artifact: message.artifact,
});
res.json({});
break;
case "status-update":
console.log("Call status:", message.status);
res.json({});
break;
case "transcript":
console.log(`[${message.role}]: ${message.transcript}`);
res.json({});
break;
default:
res.json({});
}
});
function handleToolCall(name: string, args: any): string {
// Implement your tool logic here
return `Result for ${name}`;
}
app.listen(3000, () => console.log("Webhook server running on port 3000"));from flask import Flask, request, jsonify
app = Flask(__name__)
@app.route("/vapi/webhook", methods=["POST"])
def vapi_webhook():
data = request.json
message = data.get("message", {})
msg_type = message.get("type")
if msg_type == "assistant-request":
return jsonify({
"assistant": {
"name": "Dynamic Assistant",
"firstMessage": "Hello! How can I help?",
"model": {
"provider": "openai",
"model": "gpt-4.1",
"messages": [
{"role": "system", "content": "You are a helpful assistant."}
],
},
"voice": {"provider": "vapi", "voiceId": "Elliot", "version": 2},
"transcriber": {"provider": "deepgram", "model": "nova-3", "language": "en"},
}
})
elif msg_type == "tool-calls":
results = []
for tool_call in message.get("toolCallList", []):
results.append({
"toolCallId": tool_call["id"],
"result": f"Handled {tool_call['name']}",
})
return jsonify({"results": results})
elif msg_type == "end-of-call-report":
print(f"Call ended: {message['call']['id']}")
print(f"Summary: {message.get('analysis', {}).get('summary')}")
return jsonify({})
if __name__ == "__main__":
app.run(port=3000)# Install the CLI
curl -sSL https://vapi.ai/install.sh | bash
# Terminal 1: expose the CLI listener
ngrok http 4242
# Terminal 2: forward events from the CLI to your app
vapi listen --forward-to localhost:3000/vapi/webhookngrok http 3000
# Copy the ngrok URL and set it as your server URLclaude mcp add vapi-docs -- npx -y mcp-remote https://docs.vapi.ai/_mcp/server