Test MCP Server
A simple MCP (Model Context Protocol) server for learning purposes. This server demonstrates basic MCP functionality including tools and resources with Zod validation.
What is MCP?
MCP (Model Context Protocol) is a protocol that allows AI models to interact with external tools and resources. It provides a standardized way for AI assistants to:
- Call tools (functions) to perform actions
- Read resources (files, data sources) to get information
- Provide structured responses with proper error handling
How MCP Works
- AI Model (like Cursor) wants to use a tool
- AI Model sends a JSON-RPC request to the MCP Server via stdio
- MCP Server processes the request and returns a response
- AI Model uses the response to help the user
The communication happens through JSON-RPC 2.0 over stdio - no web servers needed!
Features
This test server includes:
Tools (with Zod Validation)
echo
: Echo back input text with validationadd_numbers
: Add two numbers together with type checkingget_system_info
: Get basic system information (Node.js platform details)validate_email
: Validate email addresses using Zod's built-in email validation
Resources
file://example.txt
: A sample text file with timestampfile://example.json
: A sample JSON file with server metadata
Key Features
- ✅ Zod Validation: Runtime type checking for all tool inputs
- ✅ Error Handling: Clear error messages for invalid inputs
- ✅ JSON-RPC 2.0: Standard protocol communication
- ✅ Type Safety: TypeScript/JavaScript with proper schemas
- ✅ Resource Management: Both text and JSON resource examples
Setup
- Install dependencies:
- Make the server executable:
Usage
Running the Server
The server can be run directly:
Testing with the Client
Run the test client to see the server in action:
Using with Cursor
- Copy the configuration from
mcp_config.json
to your Cursor settings - Update the path to point to your local copy of this repository
Option 1: Using absolute path
Option 2: Using working directory (recommended)
The mcp_config.json
file in this repository serves as a template - copy it to your ~/.cursor/mcp.json
and update the paths as needed.
How It Works
Server Architecture
- Server Initialization: Creates MCP server with capabilities
- Tool Registration: Tools are registered with Zod schemas for validation
- Resource Registration: Resources are registered with URIs and metadata
- Request Handling: Server processes JSON-RPC requests via stdio
- Response Generation: Responses are formatted according to MCP protocol
Communication Flow
Example JSON-RPC Communication
Request:
Response:
Extending the Server
Adding New Tools
- Define Zod Schema:
- Add Tool Definition:
- Implement Handler:
Adding New Resources
- Add Resource Definition:
- Implement Handler:
Troubleshooting
MCP Tools Not Appearing in Cursor
- Check configuration: Ensure
~/.cursor/mcp.json
has the correct path - Restart Cursor: MCP configuration changes require a restart
- Test server: Run
node server.js
to verify it starts without errors - Check logs: Look for error messages in Cursor's developer console
Common Issues
- Path issues: Use absolute paths in MCP configuration
- Permission errors: Ensure the server file is executable (
chmod +x server.js
) - Dependency issues: Run
npm install
to ensure all packages are installed - Port conflicts: MCP uses stdio, so no port conflicts possible
Testing Your Server
Project Structure
Contributing
- Fork the repository
- Create a feature branch
- Add your tools/resources
- Test thoroughly
- Submit a pull request
License
MIT License - feel free to use this as a starting point for your own MCP servers!
This server cannot be installed
local-only server
The server can only run on the client's local machine because it depends on local resources.
A simple learning-focused MCP server that demonstrates basic functionality with tools for mathematical operations, system information, and email validation, plus sample file resources. Perfect for understanding MCP protocol basics and testing integrations.