@vantagate/mcp-server

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:

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

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:

{
  "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):

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.

License

MIT - see LICENSE

Links

• Dashboard: https://vanta-gate.com/dashboard
• Full API Docs: https://vanta-gate.com/dashboard/docs
• Privacy Policy: https://vanta-gate.com/legal/privacy-policy
• Terms of Service: https://vanta-gate.com/legal/terms-of-service