Note Taker MCP Example

// Map tools to their required features
const PREMIUM_FEATURES: Record<string, string> = {
  'delete_note': 'delete_notes',    // Requires "delete_notes" feature
  'summarize_note': 'ai_summary',   // Requires "ai_summary" feature
};

// Free features - no access check needed
const FREE_FEATURES = ['create_note', 'list_notes', 'get_note'];

import { AccessControl } from '@billai/sdk';

const accessControl = new AccessControl({
  apiKey: process.env.BILLAI_API_KEY!,
  appId: process.env.BILLAI_APP_ID!,
  baseUrl: process.env.BILLAI_BASE_URL || 'https://api.billai.dev',
  debug: !!process.env.DEBUG,
});

async function checkFeatureAccess(
  userId: string,
  toolName: string
): Promise<{ allowed: true } | { allowed: false; result: AccessDeniedResult }> {
  // Free features - always allowed
  if (FREE_FEATURES.includes(toolName)) {
    return { allowed: true };
  }

  // Get the feature name for this tool
  const featureName = PREMIUM_FEATURES[toolName];
  
  // If no feature mapping, allow by default
  if (!featureName) {
    return { allowed: true };
  }

  // Check access with BillAI
  try {
    const result = await accessControl.check(userId, featureName);

    if (result.granted) {
      return { allowed: true };
    }

    // Access denied
    return {
      allowed: false,
      result: {
        error: 'access_denied',
        message: `⚠️ Upgrade required to use "${toolName}"`,
        upgradeUrl: result.upgradeUrl,
      },
    };
  } catch (error) {
    // Fail open - allow access if service is unavailable
    console.error('Access check failed:', error);
    return { allowed: true };
  }
}

async function handleToolCall(
  toolName: string,
  args: Record<string, unknown>,
  userId: string
): Promise<ToolResult> {
  // Check access before executing
  const accessCheck = await checkFeatureAccess(userId, toolName);
  
  if (!accessCheck.allowed) {
    const { result } = accessCheck;
    console.log(`❌ Access denied for user "${userId}" on tool "${toolName}"`);
    if (result.upgradeUrl) {
      console.log(`   Upgrade URL: ${result.upgradeUrl}`);
    }
    return result;
  }

  // Execute the tool
  switch (toolName) {
    case 'create_note':
      // ... handle create
      break;
    case 'delete_note':
      // ... handle delete (premium)
      break;
    // ... other tools
  }
}