versionator-mcp 1.0.4

An MCP server that queries package registries (npm, RubyGems, PyPI, Hex.pm) for latest package versions

Versionator MCP Server

An MCP (Model Context Protocol) server that queries package registries (npm, RubyGems, PyPI, Hex.pm) to retrieve the latest release versions of packages. It follows a strict fail-hard policy and always returns current data.

Features

• Query latest versions from npm, RubyGems, PyPI, and Hex.pm
• Support for language/ecosystem aliases
• No caching - always returns current latest version
• Fail-hard error handling (no fallbacks)
• Optional package metadata (description, homepage, license)
• Configurable request timeout
• Optimized for local Claude Desktop integration

Quick Start

Option 1: Using uvx (Recommended)

The easiest way to use Versionator with Claude Desktop is via uvx:

# Install uvx if you haven't already
curl -LsSf https://astral.sh/uv/install.sh | sh

# Run Versionator directly with uvx
uvx versionator-mcp

Option 2: Install Locally

# Install from PyPI
pip install versionator-mcp

# Or install with pipx for isolated environment
pipx install versionator-mcp

Editor Integration

Claude Desktop

Add configuration to your Claude Desktop MCP settings:

Config Location:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

Recommended (uvx):

{
  "mcpServers": {
    "versionator": {
      "command": "uvx",
      "args": ["versionator-mcp"]
    }
  }
}

Alternative methods:

{
  "mcpServers": {
    "versionator": {
      "command": "pipx",
      "args": ["run", "versionator-mcp"]
    }
  }
}

Cursor

Create .cursor/mcp.json in your project root:

{
  "mcpServers": {
    "versionator": {
      "command": "uvx",
      "args": ["versionator-mcp"]
    }
  }
}

Global configuration: ~/.cursor/mcp.json

Windsurf

Edit ~/.codeium/mcp_config.json:

{
  "mcpServers": {
    "versionator": {
      "command": "uvx",
      "args": ["versionator-mcp"]
    }
  }
}

UI Method: Settings → Tools → Windsurf Settings → Add Server

Claude Code

Add to your Claude Code MCP configuration:

{
  "mcpServers": {
    "versionator": {
      "command": "uvx",
      "args": ["versionator-mcp"]
    }
  }
}

📁 Example configs: See examples/ directory for complete configuration files

Available Functions

1. get_package_version - Universal Package Version Query

Query the latest version from any supported registry.

Parameters:

• package_manager (str): Registry name or alias
• package_name (str): Name of the package

Supported Registries:

• npm (aliases: node, nodejs)
• rubygems (aliases: gem, ruby)
• pypi (aliases: pip, python)
• hex (aliases: elixir, hex.pm)

Examples:

# Query npm package
get_package_version("npm", "react")
# Returns: {"name": "react", "version": "19.1.1", ...}

# Query with alias
get_package_version("python", "django")
# Returns: {"name": "django", "version": "5.2.5", ...}

2. Registry-Specific Functions

• get_npm_package(package_name) - NPM packages
• get_ruby_gem(gem_name) - RubyGems packages
• get_python_package(package_name) - PyPI packages
• get_elixir_package(package_name) - Hex.pm packages

Response Format

All functions return a PackageVersion object:

{
  "name": "react",
  "version": "19.1.1",
  "registry": "npm",
  "registry_url": "https://registry.npmjs.org/react/latest",
  "query_time": "2025-08-13T10:30:00Z",
  "description": "React is a JavaScript library for building user interfaces.",
  "homepage": "https://react.dev/",
  "license": "MIT"
}

Error Handling

The server follows a strict FAIL HARD policy:

• No Fallbacks: Never returns cached or default values
• No Suppression: All errors propagate to the caller
• Clear Messages: Errors include context and details
• Input Validation: Validates before making API calls

Common errors:

• ValueError: Invalid package name or unknown package manager
• Exception: Package not found or API failures

Configuration

Environment variables (optional):

• VERSIONATOR_REQUEST_TIMEOUT: API request timeout in seconds (default: 30)

Troubleshooting

Common MCP Issues

1. Server not starting: Check that the command path is correct in your configuration
2. Permission errors: Ensure the Python executable has proper permissions
3. Package not found: Verify the package is installed and accessible from the command line
4. Editor not detecting server: Restart your editor after adding MCP configuration

Testing Your Setup

You can test the server directly from the command line:

# Test with uvx
uvx versionator-mcp

# Test with pipx
pipx run versionator-mcp

# Test direct installation
python -m versionator_mcp.main

The server should start and show initialization messages. Press Ctrl+C to stop.

Alternative: HTTP Server Mode

For advanced use cases, you can run Versionator as an HTTP server:

# Start HTTP server (default port 8083)
FASTMCP_PORT=8083 python -m versionator_mcp.main

# Custom port
FASTMCP_PORT=9000 python -m versionator_mcp.main

Then configure Claude Desktop with:

{
  "mcpServers": {
    "versionator": {
      "url": "http://localhost:8083/mcp",
      "transport": "http"
    }
  }
}

Note: HTTP mode requires manually starting the server before using Claude Desktop.

Development

Setup

# Clone the repository
git clone https://github.com/trianglegrrl/versionator-mcp.git
cd versionator-mcp

# Install in development mode with dev dependencies
pip install -e ".[dev]"

Running Tests

# Run tests
pytest

# Run tests with coverage
pytest --cov=versionator_mcp

# Run linting
black --check .
isort --check-only .
mypy versionator_mcp/

Testing the MCP Server

# Test stdio transport (default)
echo '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}' | python -m versionator_mcp.main

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes and add tests
4. Run the test suite (pytest)
5. Commit your changes (git commit -m 'Add amazing feature')
6. Push to the branch (git push origin feature/amazing-feature)
7. Open a Pull Request

Registry APIs

The server queries these endpoints:

• npm: https://registry.npmjs.org/{package}/latest
• RubyGems: https://rubygems.org/api/v1/versions/{gem}/latest.json
• PyPI: https://pypi.org/pypi/{package}/json
• Hex.pm: https://hex.pm/api/packages/{package}

Performance Considerations

• No Caching: Each call makes a fresh API request
• Timeout: Configurable via VERSIONATOR_REQUEST_TIMEOUT
• Concurrent Requests: Async implementation allows parallel queries
• Rate Limits: Be mindful of registry rate limits

License

This project is licensed under the MIT License - see the LICENSE file for details.

Changelog

v1.0.0

• Initial release
• Support for npm, RubyGems, PyPI, and Hex.pm
• Optimized for Claude Desktop integration
• uvx and pipx support
• Comprehensive error handling
• MCP protocol compliance