Babashka MCP Server

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

Features

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

Prerequisites

Install Babashka

Babashka can be installed in several ways:

macOS

brew install borkdude/brew/babashka

Linux

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

Windows

# Using scoop
scoop install babashka

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

Verify Installation

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*)'

Installation

# Install dependencies
npm install

# Build the MCP server
npm run build

Configuration

The server can be configured through environment variables:

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

Tools

execute

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
  }
}

Resources

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

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

Babashka Language Features

Tail Call Optimization (TCO)

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))))

Useful Resources

Official Resources

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

Community Tools & Libraries

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

Development Tools

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

Development

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.

Roadmap

1. Self-Hosted Implementation

2. Enhanced Features

3. Performance Optimizations

4. Testing & Documentation