VantaGate MCP Server & OpenAPI Integration

Human-in-the-Loop authorization for AI Agents. VantaGate intercepts high-risk actions, routes them to a human approver via Slack or Email, and returns a cryptographically-signed decision - so your agent resumes or halts with a full audit trail.

What is VantaGate?

AI agents are increasingly capable of executing consequential real-world actions: sending emails to thousands of users, deleting database records, moving money, deploying to production. VantaGate is the trust layer that ensures humans remain in control.

Agent hits risky action
        ↓
POST /v1/checkpoint  ──→  Human receives Slack/Email notification
        ↓                          ↓
   id and status              Human reviews payload & decides
        ↓                          ↓
Poll GET /v1/checkpoint/{id}  ←──  Decision recorded + payload purged
        ↓
   APPROVED → Resume workflow
   REJECTED → Halt + report reason

Key Guarantees

• < 100ms API response - your agent is never blocked waiting for I/O
• AES-256 payload encryption at rest - payload is permanently destroyed after the decision
• Zero-Retention polling - GET /checkpoint/{id} never returns the original payload
• Cryptographic audit trail - every decision is HMAC-SHA256 signed
• Stateless protocol - no SDK required; plain HTTP from any language

This Package

This package ships two integration artifacts for connecting any AI agent to VantaGate:

Prerequisites

• Node.js >= 20
• A VantaGate account: https://vanta-gate.com
• A VantaGate API key (Dashboard → Projects → New Project)

Quick Start

Option A: Use the MCP Server with Claude Desktop

The fastest path. No manual setup required.

Step 1: Get your API key from https://vanta-gate.com/dashboard/projects

Step 2: Add VantaGate to your Claude Desktop config.

Open your claude_desktop_config.json:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "vantagate": {
      "command": "npx",
      "args": ["-y", "@vantagate/mcp-server"],
      "env": {
        "VANTA_API_KEY": "YOUR_API_KEY_HERE"
      }
    }
  }
}

Step 3: Restart Claude Desktop. The tools create_vantagate_checkpoint and check_vantagate_status will appear in Claude's tool list.

Step 4: Ask Claude to do something that requires approval:

"Delete all records from the staging database where created_at < 2024-01-01"

Claude will automatically pause, create a checkpoint, and tell you to check your email or Slack for the approval notification.

Option B: Use the OpenAPI Spec (No-Code / Low-Code)

Import vanta-gate-openapi.json directly into your tool of choice.

OpenAI GPTs / Custom Actions

1. Open your GPT editor at https://platform.openai.com/gpts
2. Click "Add actions" → "Import from URL" or paste the JSON
3. Set Authentication → API Key → Header: X-API-KEY
4. Enter your VantaGate API key

The GPT will now pause before high-risk tool calls and ask for human approval.

Alice (AI Agent Platform)

1. Go to Integrations → Import OpenAPI
2. Upload or paste vanta-gate-openapi.json
3. Set header X-API-KEY to your VantaGate API key in the credential store
4. Map create_vantagate_checkpoint to your agent's "before high-risk action" trigger

n8n / Zapier

1. Add an HTTP Request node
2. Import the OpenAPI spec to auto-populate endpoints
3. Set X-API-KEY header in the credential configuration

LangChain / LlamaIndex

from langchain.tools import OpenAPITool

vanta_tool = OpenAPITool.from_openapi_spec(
    spec_path="./vanta-gate-openapi.json",
    headers={"X-API-KEY": os.environ["VANTA_API_KEY"]}
)
agent = initialize_agent([vanta_tool], llm, agent=AgentType.OPENAI_FUNCTIONS)

Available MCP Tools

create_vantagate_checkpoint

Pauses the agent workflow and routes a human approval request.

When Claude uses it: Before any high-risk action - financial operations, data deletion, production deployments, bulk communications.

Returns: checkpoint_id and step-by-step instructions for the agent.

check_vantagate_status

Polls the decision status of a pending checkpoint.

Returns: status (PENDING / APPROVED / REJECTED / RESOLVED / EXPIRED), selected_option, reject_reason, and the full audit trail.

API Reference Summary

Base URL: https://api.vanta-gate.com/v1
Authentication: X-API-KEY header

Checkpoint Status Lifecycle

PENDING → APPROVED   (human chose first/positive option)
        → REJECTED   (human rejected with optional reason)
        → RESOLVED   (human chose non-primary option)
        → EXPIRED    (timeout elapsed, no decision)

Error Codes

All errors follow the envelope:

{
  "statusCode": 400,
  "error": "Machine_Readable_Code",
  "message": "Human-readable description."
}

Subscription Tiers

Timeout values are silently clamped to your plan's maximum. A Free plan request with timeout: "7d" will be capped to 24h.

Webhooks

When a human decides, VantaGate sends a signed HTTPS POST to your callback_url (up to 5 retry attempts with exponential back-off).

Request headers:

Content-Type: application/json
X-Vanta-Signature: sha256=<HMAC-SHA256 of body>
User-Agent: VantaGate-Webhook/1.0

Signature verification (Node.js):

const crypto = require('crypto')

function verifyVantaSignature(rawBody, signature, projectSecret) {
  const expected = 'sha256=' + crypto
    .createHmac('sha256', projectSecret)
    .update(rawBody)
    .digest('hex')
  return crypto.timingSafeEqual(
    Buffer.from(expected),
    Buffer.from(signature)
  )
}

app.post('/webhook/vanta', express.raw({ type: 'application/json' }), (req, res) => {
  const sig = req.headers['x-vanta-signature']
  if (!verifyVantaSignature(req.body, sig, process.env.VANTA_PROJECT_SECRET)) {
    return res.status(401).json({ error: 'Invalid signature' })
  }
  const event = JSON.parse(req.body)
  if (event.status === 'APPROVED') {
    // ✅ Resume agent workflow
  } else if (event.status === 'REJECTED') {
    // ❌ Halt - check event.reject_reason
  }
  res.json({ received: true })
})

Your Webhook Signing Secret (VANTA_PROJECT_SECRET) is distinct from your API key. Find it in Dashboard → Project Settings.

Building from Source

# Install dependencies
npm install

# Build TypeScript
npm run build

# Run the server directly
VANTA_API_KEY=YOUR_API_KEY_HERE npm start

Advanced: MCP Config for Other Clients

Cursor / Cline / Windsurf