babashka-mcp-server

A Model Context Protocol server for interacting with Babashka, a native Clojure interpreter for scripting.

• Execute Babashka code through MCP tools
• Cache recent command results
• Access command history through MCP resources
• Configurable command timeouts

Babashka can be installed in several ways:

brew install borkdude/brew/babashka

bash < <(curl -s https://raw.githubusercontent.com/babashka/babashka/master/install)

# Using scoop
scoop install babashka

For other installation methods, see the official Babashka installation guide.

After installation, verify Babashka works:

# Check version
bb --version

# Try a simple expression
bb -e '(+ 1 2 3)'

# Run a script from string
bb -e '(defn hello [x] (str "Hello, " x "!")) (hello "World")'

# Use -i flag to process lines of input
ls | bb -i '(take 2 *input*)'

# Install dependencies
npm install

# Build the MCP server
npm run build

The server can be configured through environment variables:

• BABASHKA_PATH: Path to the Babashka executable (default: "bb")

Execute Babashka code with optional timeout:

{
  name: "execute",
  arguments: {
    code: string;      // Babashka code to execute
    timeout?: number;  // Timeout in milliseconds (default: 30000)
  }
}

Example:

{
  name: "execute",
  arguments: {
    code: "(+ 1 2 3)",
    timeout: 5000
  }
}

The server maintains a cache of recent command executions accessible through:

• babashka://commands/{index} - Access specific command results by index

Babashka supports explicit tail call optimization through the recur special form, but does not implement automatic TCO. For example:

;; This will cause stack overflow
(defn countdown [n]
  (if (zero? n)
    :done
    (countdown (dec n))))

;; This works with TCO using recur
(defn countdown [n]
  (if (zero? n)
    :done
    (recur (dec n))))

• Babashka GitHub Repository - The main Babashka project
• Babashka Book - Official documentation
• Babashka Examples - Collection of example scripts

• pod-babashka-buddy - Cryptographic API for Babashka
• bb-clis - Collection of useful Babashka CLI scripts
• bb-scripts - Various utility scripts for Babashka

• setup-babashka - GitHub Actions for installing Babashka
• babashka-docker-action - Run Babashka scripts in GitHub Actions

This server is designed to eventually become self-hosting, meaning it will be rewritten in Babashka itself. The current TypeScript implementation serves as a reference and starting point.

1. Self-Hosted Implementation

   • Rewrite the MCP server in Babashka
   • Leverage Babashka's native capabilities for better performance
   • Remove Node.js dependency
   • Maintain full compatibility with MCP protocol
   • Support all current features:
     • Command execution
     • Resource management
     • Command history
     • Timeout handling

2. Enhanced Features

   • Add support for Babashka pods
   • Implement file watching capabilities
   • Add REPL integration
   • Support for multiple Babashka instances

3. Performance Optimizations

   • Implement caching strategies
   • Optimize resource usage
   • Reduce startup time

4. Testing & Documentation

   • Comprehensive test suite
   • API documentation
   • Usage examples
   • Performance benchmarks