Show HN: MCP Server SDK in Bash (~250 lines, zero runtime)

Summary

🐚 MCP Server in Bash A lightweight, zero-overhead implementation of the Model Context Protocol (MCP) server in pure Bash. Why? Most MCP servers are just API wrappers with schema conversion. This implementation provides a zero-overhead alternative to Node.js, Python, or other heavy runtimes. 📋 Features ✅ Full JSON-RPC 2.0 protocol over stdio ✅ Complete MCP protocol implementation ✅ Dynamic tool discovery via function naming convention ✅ External configuration via JSON files ✅ Easy to extend with custom tools 🔧 Requirements Bash shell jq for JSON processing ( brew install jq on macOS) 🚀 Quick Start Clone the repo git clone https://github.com/muthuishere/mcp-server-bash-sdk cd mcp-server-bash-sdk Make scripts executable chmod +x mcpserver_core.sh moviemcpserver.sh Try it out echo ' {"jsonrpc": "2.0", "method": "tools/call", "params": {"name": "get_movies"}, "id": 1} ' | ./moviemcpserver.sh 🏗️ Architecture ┌─────────────┐ ┌────────────────────────┐ │ MCP Host │ │ MCP Server │ │ (AI System) │◄──────► │ (moviemcpserver.sh) │ └─────────────┘ stdio └────────────────────────┘ │ ┌───────┴──────────┐ ▼ ▼ ┌─────────────────┐ ┌───────────────┐ │ Protocol Layer │ │ Business Logic│ │(mcpserver_core.sh)│ │(tool_* funcs)│ └─────────────────┘ └───────────────┘ │ │ ▼ ▼ ┌─────────────────┐ ┌───────────────┐ │ Configuration │ │ External │ │ (JSON Files) │ │ Services/APIs │ └─────────────────┘ └───────────────┘ mcpserver_core.sh : Handles JSON-RPC and MCP protocol : Handles JSON-RPC and MCP protocol moviemcpserver.sh : Contains business logic functions : Contains business logic functions assets/: JSON configuration files 🔌 Creating Your Own MCP Server Create your business logic file (e.g., weatherserver.sh ) #! /bin/bash # Weather API implementation # Source the core MCP server source " $( dirname " ${BASH_SOURCE[0]} " ) /mcpserver_core.sh " # Access environment variables API_KEY= " ${MCP_API_KEY :- default_key} " # Weather tool implementation tool_get_weather () { local args= " $1 " loc...