What it does
A minimal JSON-RPC 2.0 compliant MCP server implementing the Model-Context-Protocol. The server provides basic echo functionality with CORS enabled for cross-origin requests. It exposes a simple initialization protocol and runs on port 4333 by default. Designed as a reference implementation, it prioritizes clarity over production-grade features, making it useful for understanding how MCP servers work and how they interact with clients via the JSON-RPC 2.0 standard.
Who it's for
Developers new to MCP who want to understand how a JSON-RPC 2.0 server works at a fundamental level. Also useful for those prototyping custom MCP servers and needing a minimal, well-structured starting point. Less suited for production deployments due to limited feature set and unclear maintenance status; better for learning, testing, and as a template foundation.
Common use cases
- Learn MCP server architecture and JSON-RPC 2.0 protocol fundamentals
- Use as a template for building custom MCP servers with domain-specific tools
- Test MCP client implementations against a simple, predictable reference server
- Understand MCP initialization flow and basic request/response handling patterns
Setup pitfalls
- Runs on port
4333; ensure the port is available and not blocked by firewall or existing services - No CI pipeline; last commit was 477 days ago, so maintenance status is unclear before using in production
- Reads the filesystem; apply appropriate permission controls and consider sandboxing depending on deployment context
- Minimal documentation and feature set; intended as a learning reference rather than for production workloads