Integrating External Tools

Learn how to connect your MCP Server agents to external services, databases, and APIs.

Overview

MCP Server supports integration with:

SQL and NoSQL databases

REST and GraphQL APIs

File systems and cloud storage

Third-party services (Stripe, SendGrid, etc.)

Custom webhooks and automations

Database Integration

PostgreSQL

import { MCPClient } from '@mcpserver/sdk';

const client = new MCPClient({
  apiKey: process.env.MCP_API_KEY,
});

// Configure database connection
await client.databases.connect({
  type: 'postgresql',
  connection: {
    host: process.env.DB_HOST,
    port: 5432,
    database: process.env.DB_NAME,
    user: process.env.DB_USER,
    password: process.env.DB_PASSWORD,
  },
});

// Query the database
const results = await client.databases.query({
  sql: 'SELECT * FROM customers WHERE active = true',
});

MongoDB

await client.databases.connect({
  type: 'mongodb',
  connection: {
    uri: process.env.MONGODB_URI,
  },
});

const documents = await client.databases.find({
  collection: 'users',
  filter: { status: 'active' },
});

API Integration

REST APIs

await client.apis.register({
  name: 'stripe',
  baseUrl: 'https://api.stripe.com',
  auth: {
    type: 'bearer',
    token: process.env.STRIPE_API_KEY,
  },
  endpoints: [
    {
      name: 'list-customers',
      method: 'GET',
      path: '/v1/customers',
    },
    {
      name: 'create-payment-intent',
      method: 'POST',
      path: '/v1/payment_intents',
    },
  ],
});

// Use the API
const customers = await client.apis.call('stripe', 'list-customers');

GraphQL

await client.apis.register({
  name: 'github',
  type: 'graphql',
  endpoint: 'https://api.github.com/graphql',
  auth: {
    type: 'bearer',
    token: process.env.GITHUB_TOKEN,
  },
});

const result = await client.apis.query('github', 

  query {
    viewer {
      repositories(first: 10) {
        nodes {
          name
          description
        }
      }
    }
  }
);

File System Access

// Read files
const content = await client.files.read('/path/to/file.json');

// Write files
await client.files.write('/path/to/output.txt', 'Hello, world!');

// List directory
const files = await client.files.list('/path/to/directory');

Cloud Storage

AWS S3

await client.storage.connect({
  provider: 's3',
  config: {
    accessKeyId: process.env.AWS_ACCESS_KEY,
    secretAccessKey: process.env.AWS_SECRET_KEY,
    region: 'us-east-1',
  },
});

// Upload file
await client.storage.upload({
  bucket: 'my-bucket',
  key: 'uploads/file.pdf',
  body: fileBuffer,
});

// Download file
const file = await client.storage.download({
  bucket: 'my-bucket',
  key: 'uploads/file.pdf',
});

Security Best Practices

1. Never expose API keys in client-side code

2. Use environment variables for sensitive credentials

3. Implement rate limiting to prevent abuse

4. Validate all inputs before passing to external services

5. Use HTTPS for all API communications

Error Handling

try {
  const result = await client.apis.call('external-service', 'endpoint');
} catch (error) {
  if (error.code === 'RATE_LIMIT_EXCEEDED') {
    // Wait and retry
    await sleep(5000);
    return retry();
  } else if (error.code === 'UNAUTHORIZED') {
    // Refresh credentials
    await refreshAuth();
  } else {
    // Log and handle
    console.error('API error:', error);
  }
}

Next Steps

Authentication & Security

Scaling Your Application

Troubleshooting Guide