VantaGate MCP Server & OpenAPI Integration

![npm version](https://www.npmjs.com/package/@vantagate/mcp-server) ![License: MIT](LICENSE) ![Node.js >= 20](https://nodejs.org)

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:

| Artifact | File | Best for | |---|---|---| | OpenAPI 3.0 Spec | vanta-gate-openapi.json | No-code tools, OpenAI GPTs, Alice, n8n, Zapier | | MCP Server | src/index.ts / dist/index.js | Claude Desktop, Cursor, Cline, any MCP-compatible agent |

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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

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

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

Alice (AI Agent Platform)

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

n8n / Zapier

Add an HTTP Request node
Import the OpenAPI spec to auto-populate endpoints
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.

| Parameter | Type | Required | Description | |---|---|---|---| | title | string | ✅ | Short title shown to approver. Max 200 chars. | | payload | object | ✅ | Full JSON context for the decision. Encrypted + purged after decision. | | description | string | ❌ | Additional context below the title. Max 1000 chars. | | options | string[] | ❌ | Decision options. First = approve action. Default: ["Approve", "Reject"]. Min 2, max 5. | | timeout | string | ❌ | Auto-expire duration: 30m, 4h, 2d. Default: 24h. | | notify_email | string | ❌ | Email address for magic-link notification. | | slack_webhook_url | string | ❌ | Slack webhook URL (Pro/Scale plans). From Dashboard → Add to Slack. | | callback_url | string | ❌ | Your HTTPS endpoint for signed decision webhook. |

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

`check_vantagate_status`

Polls the decision status of a pending checkpoint.

| Parameter | Type | Required | Description | |---|---|---|---| | checkpoint_id | string | ✅ | The ID from create_vantagate_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

| Method | Endpoint | Description | |---|---|---| | POST | /checkpoint | Create a checkpoint - pauses agent | | GET | /checkpoint/{id} | Poll for human decision | | GET | /checkpoint/secure/{token} | Decision UI (internal - magic link) | | POST | /checkpoint/secure/{token}/decide | Submit decision (internal - decision UI) |

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

| HTTP | Code | Description | |---|---|---| | 400 | Invalid_Webhook_URL | slack_webhook_url must start with https://hooks.slack.com/ | | 400 | Invalid_Callback_URL | callback_url is malformed or points to private IP | | 400 | Invalid_Decision | Decision value not in checkpoint's options array | | 400 | Validation_Error | Request body field validation failure | | 401 | Unauthorized | Missing, invalid, or rotated API key | | 402 | Upgrade_Required | Feature requires Pro or Scale plan | | 403 | Forbidden | API key doesn't match the checkpoint's project | | 404 | Not_Found | Checkpoint ID or token does not exist | | 409 | Already_Decided | Decision already recorded for this checkpoint | | 410 | Checkpoint_Expired | Timeout window has passed | | 429 | Rate_Limited | Too many requests - back off and retry |

All errors follow the envelope: ``json { "statusCode": 400, "error": "Machine_Readable_Code", "message": "Human-readable description." } ``

---

Subscription Tiers

| Feature | Free | Pro ($49/mo) | Scale ($199/mo) | |---|---|---|---| | Checkpoints/month | 50 | 2,500 | 25,000 | | Email notifications | ✅ | ✅ | ✅ | | Slack notifications | ❌ | ✅ | ✅ | | Webhook callbacks | ✅ | ✅ | ✅ | | Max timeout | 24h | 7 days | 30 days | | Log retention | 7 days | 90 days | 365 days |

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): ```javascript 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

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

With local build (development)

{
  "mcpServers": {
    "vantagate": {
      "command": "node",
      "args": ["/absolute/path/to/dist/index.js"],
      "env": {
        "VANTA_API_KEY": "YOUR_API_KEY_HERE"
      }
    }
  }
}

---

Security

Your X-API-KEY is hashed server-side - VantaGate never stores plaintext keys.
Your slack_webhook_url is sent per-request and purged atomically after the decision. Zero retention.
All payload data is encrypted at rest with AES-256 and destroyed after the human decision. It cannot be reconstructed.
callback_url is validated against private IP ranges (SSRF prevention).
All webhook deliveries are signed with HMAC-SHA256. Always verify signatures.

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License

MIT - see LICENSE

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vantagate-mcp-server