Nexus MCP Server

<!-- markdownlint-disable MD033 MD041 --> <div align="center"> # 🔍 Nexus MCP Server **AI integration without the complexity** [](https://www.npmjs.com/package/nexus-mcp)  [](https://opensource.org/licenses/MIT) [](https://www.typescriptlang.org/) [](https://modelcontextprotocol.io/) [](https://coderabbit.ai) _Intelligent AI model search and discovery with zero-install simplicity_ [Quick Start](#-quick-start) • [Features](#-features) • [Documentation](#-documentation) • [Contributing](#-contributing) </div> --- ## What is Nexus? Nexus is a **Model Context Protocol (MCP) server** that provides AI-powered web search functionality through the OpenRouter API. It integrates with MCP-compatible clients including Claude Desktop and Cursor, providing search capabilities via the Perplexity Sonar model family. ### Key Characteristics - **Zero-install deployment**: Executable via `npx` with no build requirements - **OpenRouter integration**: Uses Perplexity Sonar models for web search with citations - **MCP protocol compliance**: Implements standard MCP tool and resource interfaces - **Production architecture**: Includes request caching, deduplication, retry logic, and error handling - **Type-safe implementation**: Full TypeScript coverage with strict type checking ## Features ### Deployment - NPX-based execution with zero local installation - Cross-platform compatibility (macOS, Linux, Windows) - Node.js 18+ runtime requirement - Automated version updates via npm registry ### Search Capabilities - Perplexity Sonar model family integration - Real-time web search with current information - Structured citation extraction from responses - Configurable model parameters (temperature, max tokens, penalties) ### Architecture - Comprehensive error handling with typed error classes - Request caching with configurable TTL - Request deduplication for concurrent identical queries - Automatic retry logic with exponential backoff - Winston-based structured logging - TypeScript strict mode implementation with full type coverage ## Quick Start ### Prerequisites - Node.js 18 or higher - OpenRouter API key ([register at openrouter.ai](https://openrouter.ai)) ### NPX Installation Execute the server without local installation: ```bash # Set your OpenRouter API key export OPENROUTER_API_KEY=your-api-key-here # Run the server via NPX npx nexus-mcp ``` The server starts and listens for MCP client connections via STDIO transport. ### Testing the NPX Installation ```bash # Test the CLI help npx nexus-mcp --help # Test the version npx nexus-mcp --version # Run with your API key OPENROUTER_API_KEY=your-key npx nexus-mcp ``` ## Alternative: Local Development Installation For local development or customization: 1. Clone the repository: ```bash git clone https://github.com/adawalli/nexus.git cd nexus ``` 2. Install dependencies: ```bash npm install ``` 3. Build the server: ```bash npm run build ``` 4. Configure your OpenRouter API key: ```bash # Copy the example environment file cp .env.example .env # Edit .env and add your actual API key # OPENROUTER_API_KEY=your-api-key-here ``` 5. Test the server: ```bash npm start ``` ## Integration with MCP Clients ### NPX-Based Integration (Recommended) Configure MCP clients to execute the server via NPX: ### Claude Code Configuration in `~/.claude/mcp_settings.json`: ```json { "mcpServers": { "nexus": { "command": "npx", "args": ["nexus-mcp"], "env": { "OPENROUTER_API_KEY": "your-api-key-here" } } } } ``` Restart Claude Code after configuration changes. ### Cursor Add server configuration in Cursor's MCP settings: - **Name**: `nexus` - **Command**: `npx` - **Args**: `["nexus-mcp"]` - **Environment Variables**: `OPENROUTER_API_KEY=your-api-key-here` Restart Cursor after configuration changes. ### Generic MCP Client Configuration Standard MCP client connection parameters: - **Transport**: stdio - **Command**: `npx` - **Args**: `["nexus-mcp"]` - **Environment**: `OPENROUTER_API_KEY=your-api-key-here` ### Alternative: Local Installation If you prefer using a local installation (after following the local development setup): ```json { "mcpServers": { "nexus": { "command": "node", "args": ["/path/to/nexus-mcp/dist/cli.js"], "env": { "OPENROUTER_API_KEY": "your-api-key-here" } } } } ``` ## Usage Once integrated, you can use the search tool in your MCP client: ### Basic Search ``` Use the search tool to find information about "latest developments in AI" ``` ### Advanced Search with Parameters ``` Search for "climate change solutions" using: - Model: perplexity/sonar - Max tokens: 2000 - Temperature: 0.3 ``` ## Available Tools ### `search` The main search tool that provides AI-powered web search capabilities. **Parameters:** - `query` (required): Search query (1-2000 characters) - `model` (optional): Perplexity model to use (default: "perplexity/sonar") - `maxTokens` (optional): Maximum response tokens (1-4000, default: 1000) - `temperature` (optional): Response randomness (0-2, default: 0.7) **Example Response:** ``` Based on current information, here are the latest developments in AI... [Detailed AI-generated response with current information] --- **Search Metadata:** - Model: perplexity/sonar - Response time: 1250ms - Tokens used: 850 - Sources: 5 found ``` ## Configuration ### Environment Variables - `OPENROUTER_API_KEY` (required): Your OpenRouter API key - `NODE_ENV` (optional): Environment setting (development, production, test) - `LOG_LEVEL` (optional): Logging level (debug, info, warn, error) ### Advanced Configuration The server supports additional configuration through environment variables: - `OPENROUTER_TIMEOUT_MS`: Request timeout in milliseconds (default: 30000) - `OPENROUTER_MAX_RETRIES`: Maximum retry attempts (default: 3) - `OPENROUTER_BASE_URL`: Custom OpenRouter API base URL ## Resources The server provides a configuration status resource at `config://status` that shows: - Server health status - Configuration information (with masked API key) - Search tool availability - Server uptime and version ## Troubleshooting ### NPX-Specific Issues **"npx: command not found"** - Ensure Node.js 18+ is installed: `node --version` - Update npm: `npm install -g npm@latest` **"Cannot find package 'nexus-mcp'"** - The package may not be published yet. Use local installation instead - Verify network connectivity for npm registry access **NPX takes a long time to start** - This is normal on first run as NPX downloads the package - Subsequent runs will be faster due to caching - For faster startup, use local installation instead **"Permission denied" errors with NPX** - Try: `npx --yes nexus-mcp --stdio` - Or set npm permissions: `npm config set user 0 && npm config set unsafe-perm true` ### Common Issues **"Search functionality is not available"** - Ensure `OPENROUTER_API_KEY` environment variable is set - Verify your API key is valid at [OpenRouter](https://openrouter.ai) - Check the server logs for initialization errors **"Authentication failed: Invalid API key"** - Double-check your API key format and validity - Ensure the key has sufficient credits/permissions - Test the key directly at OpenRouter dashboard **"Rate limit exceeded"** - Wait for the rate limit to reset (usually 1 minute) - Consider upgrading your OpenRouter plan for higher limits - Monitor usage in your OpenRouter dashboard **Connection timeouts** - Check your internet connection - The server will automatically retry failed requests - Increase timeout if needed: `OPENROUTER_TIMEOUT_MS=60000` **MCP client can't connect to server** - Verify your MCP configuration uses the correct command and arguments - Check that Node.js 18+ is available in your MCP client's environment - Ensure the API key is properly set in the environment variables ### Debug Logging Enable debug logging by: **For local development:** Add `LOG_LEVEL=debug` to your `.env` file **For MCP clients:** Add `LOG_LEVEL: "debug"` to the `env` section of your MCP configuration This will provide detailed information about: - Configuration loading - API requests and responses - Error details and stack traces - Performance metrics ### Testing Connection You can test if the server is working by checking the configuration status resource in your MCP client, or by running a simple search query. ## Development For developers working on this server: ```bash # Development with hot reload npm run dev # Run tests npm test # Run tests with coverage npm run test:coverage # Lint code npm run lint # Format code npm run format ``` ## API Costs OpenRouter charges for API usage based on token consumption: - **Pricing**: See current rates at [OpenRouter Models](https://openrouter.ai/models) - **Monitoring**: Usage tracking available in OpenRouter dashboard - **Limits**: Configure spending limits in OpenRouter account settings - **Optimization**: Server implements response caching and request deduplication to minimize redundant API calls ## 📚 Documentation <div align="center"> | 📖 **Guide** | 🔗 **Link** | 📝 **Description** | | ------------------- | ------------------------------------------- | -------------------------------- | | **Quick Start** | [Getting Started](#-quick-start) | Zero-install setup in 30 seconds | | **API Reference** | [MCP Tools](CLAUDE.md#development-commands) | Complete command reference | | **Configuration** | [Environment Setup](#configuration) | Advanced configuration options | | **Contributing** | [Contributing Guide](CONTRIBUTING.md) | Join our open source community | | **Troubleshooting** | [Common Issues](#troubleshooting) | Solutions to common problems | </div> ## 🤝 Contributing We welcome contributions from developers of all experience levels! <table> <tr> <td width="33%"> ### 🚀 **Get Started** - Fork the repository - Read our [Contributing Guide](CONTRIBUTING.md) - Check out [good first issues](https://github.com/search?q=repo%3Anexus-mcp+label%3A%22good+first+issue%22&type=issues) </td> <td width="33%"> ### 🐛 **Report Issues** - [Bug Reports](https://github.com/adawalli/nexus/issues/new) - [Feature Requests](https://github.com/adawalli/nexus/issues/new) - [Ask Questions](https://github.com/adawalli/nexus/issues/new) </td> <td width="33%"> ### 💬 **Join Community** - [GitHub Discussions](https://github.com/adawalli/nexus/discussions) - [Code of Conduct](CODE_OF_CONDUCT.md) - [Roadmap & Project Board](https://github.com/adawalli/nexus/projects) </td> </tr> </table> ### 🌟 Recognition Contributors are recognized in our: - [Contributors list](https://github.com/adawalli/nexus/graphs/contributors) - Release notes for significant contributions - Community spotlights and testimonials ## 🔗 Related Projects - [Model Context Protocol](https://modelcontextprotocol.io) - The standard we implement - [OpenRouter](https://openrouter.ai) - Our AI model provider - [Claude Desktop](https://claude.ai) - Primary MCP client - [Cursor](https://cursor.sh) - AI-powered code editor with MCP support ## 📞 Support & Community <div align="center"> | 💬 **Need Help?** | 🔗 **Resource** | | -------------------- | ---------------------------------------------------------------------------------------------------- | | **Quick Questions** | [GitHub Discussions](https://github.com/adawalli/nexus/discussions) | | **Bug Reports** | [GitHub Issues](https://github.com/adawalli/nexus/issues) | | **Documentation** | [OpenRouter Docs](https://openrouter.ai/docs) • [MCP Specification](https://modelcontextprotocol.io) | | **Feature Requests** | [Enhancement Proposals](https://github.com/adawalli/nexus/issues/new) | </div> ## 📄 License **MIT License** - see [LICENSE](LICENSE) file for details. --- <div align="center"> **Made with ❤️ by the open source community** [⭐ Star us on GitHub](https://github.com/adawalli/nexus) • [📦 View on NPM](https://www.npmjs.com/package/nexus-mcp) • [📚 Read the Docs](CLAUDE.md) _Nexus: AI integration without the complexity_ [](https://star-history.com/#adawalli/nexus&Date) </div>