​
MCP Server

The MCP Server is responsible for hosting resources that can be consumed by MCP clients. It provides a standardized way to register, manage, and serve resources with proper validation.

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Creating a Server

To create an MCP server, you need to define resource schemas and create a server configuration:

import { MCPServer } from '@repo/mcp';
import { z } from 'zod';

// Define resource schemas
const userSchema = z.object({
  id: z.string(),
  type: z.literal('user'),
  attributes: z.object({
    name: z.string(),
    email: z.string().email(),
    role: z.enum(['admin', 'user', 'guest'])
  }).optional()
});

// Create server configuration
const serverConfig = {
  name: 'UserService',
  description: 'Provides user context for AI models',
  resources: {
    user: MCPServer.createResourceDefinition(userSchema, {
      description: 'User resource',
      examples: [{
        id: 'user-123',
        type: 'user',
        attributes: {
          name: 'John Doe',
          email: 'john@example.com',
          role: 'admin'
        }
      }]
    })
  }
};

// Initialize server
const server = new MCPServer(serverConfig);

​
Registering Resources

Once you have created a server, you can register resources with it:

// Register a single resource
server.registerResource({
  id: 'user-123',
  type: 'user',
  attributes: {
    name: 'John Doe',
    email: 'john@example.com',
    role: 'admin'
  }
});

// Register multiple resources
server.registerResources([
  {
    id: 'user-456',
    type: 'user',
    attributes: {
      name: 'Jane Smith',
      email: 'jane@example.com',
      role: 'user'
    }
  },
  {
    id: 'user-789',
    type: 'user',
    attributes: {
      name: 'Bob Johnson',
      email: 'bob@example.com',
      role: 'guest'
    }
  }
]);

​
Server Methods

The MCP server provides several methods for managing resources:

​
listResources

Lists all available resources or resources of a specific type:

// List all resources
const allResources = server.listResources();

// List resources with pagination
const paginatedResources = server.listResources({
  cursor: 'previousCursor',
  limit: 10
});

// List resources of a specific type
const userResources = server.listResources({
  type: 'user'
});

​
getResource

Retrieves a specific resource by its type and ID:

// Get a specific resource
const user = server.getResource('user', 'user-123');

​
updateResource

Updates an existing resource:

// Update a resource
server.updateResource({
  id: 'user-123',
  type: 'user',
  attributes: {
    name: 'John Doe Updated',
    email: 'john.updated@example.com',
    role: 'admin'
  }
});

​
deleteResource

Deletes a resource by its type and ID:

// Delete a resource
server.deleteResource('user', 'user-123');

​
Integration with API Routes

You can integrate the MCP server with API routes to create a fully functional MCP API:

// In your API route (e.g., app/api/mcp/route.ts)
import { MCPServer } from '@repo/mcp';
import { NextRequest, NextResponse } from 'next/server';

// Create server instance (or import from a shared location)
const server = new MCPServer({ /* config */ });

export async function GET(request: NextRequest) {
  const { searchParams } = new URL(request.url);
  const type = searchParams.get('type');
  const id = searchParams.get('id');
  const cursor = searchParams.get('cursor');
  const limit = searchParams.get('limit') ? parseInt(searchParams.get('limit')!) : undefined;

  // Handle resource listing
  if (!id) {
    const resources = server.listResources({
      type: type || undefined,
      cursor: cursor || undefined,
      limit
    });
    return NextResponse.json(resources);
  }

  // Handle resource retrieval
  if (type && id) {
    const resource = server.getResource(type, id);
    if (!resource) {
      return NextResponse.json({ error: 'Resource not found' }, { status: 404 });
    }
    return NextResponse.json(resource);
  }

  return NextResponse.json({ error: 'Invalid request' }, { status: 400 });
}

export async function POST(request: NextRequest) {
  const body = await request.json();
  
  try {
    const resource = server.registerResource(body);
    return NextResponse.json(resource, { status: 201 });
  } catch (error) {
    return NextResponse.json({ error: (error as Error).message }, { status: 400 });
  }
}

​
Best Practices

  1. Resource Definition: Define clear schemas for your resources with detailed descriptions and examples
  2. Resource Validation: Always validate resources before registering them with the server
  3. Error Handling: Implement proper error handling for validation failures
  4. Pagination: Use pagination for large resource collections
  5. Documentation: Document your resource types and their schemas for other developers