APort Policy Gate Example - MCP Server

Example MCP server that demonstrates APort policy enforcement for AI agent tool calls using Simple Mode (passport check + policy verification).

Note: This example uses Simple Mode, suitable for internal tools and dev environments. Secure Mode (with SCA requirements) will be added in Month 2 for enterprise/external tools.

Features

• 🔐 Policy enforcement using APort before tool execution (Simple Mode)
• 🛠️ Two example tools: merge_pull_request and process_refund
• ✅ Real-time authorization with <100ms latency
• 📝 Immutable audit trail with decision IDs
• 🔌 Compatible with Claude Desktop, VS Code, and any MCP client

Quick Start

1. Install

npm install -g @aporthq/mcp-policy-gate-example

2. Configure Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "aport-protected-tools": {
      "command": "npx",
      "args": [
        "@aporthq/mcp-policy-gate-example"
      ],
      "env": {
        "APORT_BASE_URL": "https://api.aport.io"
      }
    }
  }
}

3. Register Agent Passport

Get an agent passport from aport.io:

curl -X POST https://api.aport.io/api/passports \
  -H "Content-Type: application/json" \
  -d '{
    "owner_id": "your_org_id",
    "capabilities": ["code.repository.merge", "finance.payment.refund"],
    "assurance_level": "L2"
  }'

4. Use in Claude

User: Merge PR #123 in my-org/my-repo to main branch

Claude: I'll use the merge_pull_request tool...
[Policy check happens automatically]
✅ Pull request #123 merged to main in my-org/my-repo
Decision ID: dec_1234567890

Architecture (Simple Mode)

Security Model: Passport-based verification with policy enforcement.

sequenceDiagram
    participant Claude
    participant MCP Server
    participant APort
    participant Tool (GitHub API)

    Claude->>MCP Server: merge_pull_request(agent_id, repo, pr_number)
    Note over MCP Server: Extract agent_id from request
    MCP Server->>APort: POST /api/verify/policy/code.repository.merge.v1
    Note over APort: 1. Verify passport exists
    Note over APort: 2. Evaluate policy locally
    APort-->>MCP Server: { allow: true, decision_id: "dec_..." }
    MCP Server->>Tool: Execute merge (policy approved)
    Tool-->>MCP Server: Success
    MCP Server-->>Claude: ✅ PR merged (decision_id: dec_...)

Policy Enforcement (Simple Mode)

Every tool call is protected by APort policies using Simple Mode:

Endpoint: /api/verify/policy/{pack_id}

Security Flow:

1. Extract agent_id from request context
2. Verify passport exists and is active
3. Evaluate policy locally (<20ms)
4. Return allow/deny decision

Use Case: Internal tools, dev environments, CI/CD pipelines, trusted agents

merge_pull_request → code.repository.merge.v1

• Requires capability: code.repository.merge or repo.pr.create + repo.merge
• Minimum assurance level: L2
• Validates: repository access, branch protection, PR size limits

process_refund → finance.payment.refund.v1

• Requires capability: finance.payment.refund
• Minimum assurance level: L2
• Validates: amount limits, currency support, daily caps, reason codes

When to Upgrade to Secure Mode (Month 2):

• External MCP servers (tools from outside your organization)
• Payment processors requiring cryptographic proof
• Data exports with PII/sensitive data
• Enterprise APIs with regulatory requirements

Example: Policy Denial

User: Process a $100,000 refund for order 123

Claude: I'll process that refund...
[Policy check fails]
❌ Policy denied: Amount exceeds daily cap of $50,000
Decision ID: dec_0987654321

Environment Variables

• APORT_BASE_URL: APort registry URL (default: https://api.aport.io)
• APORT_TIMEOUT_MS: Request timeout in milliseconds (default: 5000)

Local Development

# Clone repo
git clone https://github.com/aporthq/mcp-policy-gate-example.git
cd mcp-policy-gate-example

# Install dependencies
npm install

# Build TypeScript
npm run build

# Run locally
npm start

# Or run in dev mode with auto-reload
npm run dev

Integration with Other MCP Clients

VS Code (Cline Extension)

Add to settings.json:

{
  "cline.mcpServers": {
    "aport-protected-tools": {
      "command": "npx",
      "args": ["@aporthq/mcp-policy-gate-example"]
    }
  }
}

Custom MCP Client

import { Client } from '@modelcontextprotocol/sdk/client/index.js';
import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js';

const transport = new StdioClientTransport({
  command: 'npx',
  args: ['@aporthq/mcp-policy-gate-example'],
});

const client = new Client({
  name: 'my-client',
  version: '1.0.0',
}, {
  capabilities: {},
});

await client.connect(transport);

// Call tool (agent_id required)
const result = await client.request({
  method: 'tools/call',
  params: {
    name: 'merge_pull_request',
    arguments: {
      agent_id: 'ap_a2d10232c6534523812423eec8a1425c',
      repository: 'my-org/my-repo',
      pr_number: 123,
      base_branch: 'main',
    },
  },
});

console.log(result);

License

MIT