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.
- ✅ 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
- Bash shell
jqfor JSON processing (brew install jqon macOS)
- 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┌─────────────┐ ┌────────────────────────┐
│ 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
- moviemcpserver.sh: Contains business logic functions
- assets/: JSON configuration files
When implementing tool functions for the MCP server, follow these guidelines:
- Naming Convention: All tool functions must be prefixed with
tool_followed by the same name defined in tools_list.json - Parameters: Each function should accept a single parameter
$1containing JSON arguments - Success Pattern: For successful operations, echo the result and return 0
- Error Pattern: For validation errors, echo an error message and return 1
- Automatic Discovery: All tool functions are automatically exposed to the MCP server based on tools_list.json
- Create your business logic file (e.g.,
weatherserver.sh)
#!/bin/bash
# Weather API implementation
# Override configuration paths BEFORE sourcing the core
MCP_CONFIG_FILE="$(dirname "${BASH_SOURCE[0]}")/assets/weatherserver_config.json"
MCP_TOOLS_LIST_FILE="$(dirname "${BASH_SOURCE[0]}")/assets/weatherserver_tools.json"
MCP_LOG_FILE="$(dirname "${BASH_SOURCE[0]}")/logs/weatherserver.log"
# MCP Server Tool Function Guidelines:
# 1. Name all tool functions with prefix "tool_" followed by the same name defined in tools_list.json
# 2. Function should accept a single parameter "$1" containing JSON arguments
# 3. For successful operations: Echo the expected result and return 0
# 4. For errors: Echo an error message and return 1
# 5. All tool functions are automatically exposed to the MCP server based on tools_list.json
# Source the core MCP server implementation
source "$(dirname "${BASH_SOURCE[0]}")/mcpserver_core.sh"
# Access environment variables
API_KEY="${MCP_API_KEY:-default_key}"
# Tool: Get current weather for a location
# Parameters: Takes a JSON object with location
# Success: Echo JSON result and return 0
# Error: Echo error message and return 1
tool_get_weather() {
local args="$1"
local location=$(echo "$args" | jq -r '.location')
# Parameter validation
if [[ -z "$location" ]]; then
echo "Missing required parameter: location"
return 1
fi
# Call external API
local weather=$(curl -s "https://api.example.com/weather?location=$location&apikey=$API_KEY")
echo "$weather"
return 0
}
# Start the MCP server
run_mcp_server "$@"- Create
assets/weatherserver_tools.json
{
"tools": [
{
"name": "get_weather",
"description": "Get current weather for a location",
"parameters": {
"type": "object",
"properties": {
"location": {
"type": "string",
"description": "City name or coordinates"
}
},
"required": ["location"]
}
}
]
}- Create
assets/weatherserver_config.json
{
"protocolVersion": "0.1.0",
"serverInfo": {
"name": "WeatherServer",
"version": "1.0.0"
},
"capabilities": {
"tools": {
"listChanged": true
}
},
"instructions": "This server provides weather information."
}- Make your file executable
chmod +x weatherserver.sh- Update VS Code settings.json
- Use with GitHub Copilot Chat
/mcp my-weather-server get weather for New York
- No concurrency/parallel processing
- Limited memory management
- No streaming responses
- Not designed for high throughput
For AI assistants and local tool execution, these aren't blocking issues.
This project is licensed under the MIT License - see the LICENSE file for details.