Which integrations are available for this server?

Allows executing sandboxed code to interact with Slack's API, enabling capabilities such as fetching channel history and polling for specific messages while optimizing token usage through local data processing.

How do I use MCX (Modular Code Execution)?

1. Click on "Install Server". 2. Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state. 3. In the chat, type @ followed by the MCP server name and your instructions, e.g., "@MCX (Modular Code Execution) fetch the last 50 orders and calculate the total revenue by category" That's it! The server will respond to your query, and you can continue using it as needed. Here is a step-by-step guide with screenshots.

MCX - Modular Code Execution

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MCP server that lets AI agents execute code instead of calling tools directly.

Based on Anthropic's code execution article.

The Problem

Traditional MCP has two inefficiencies:

Tool definition overload - Loading all tool definitions floods context
Intermediate result bloat - Every API response passes through the model

The Solution

Instead of calling tools directly, the agent writes code that runs in a sandbox:

const invoices = await api.getInvoices({ limit: 100 });
return {
  count: invoices.length,
  total: sum(invoices, 'amount'),
  byStatus: count(invoices, 'status')
};
// Returns ~50 tokens instead of 50,000

Result: 98% token reduction by filtering data inside the execution environment.

Installation

# Install globally with bun
bun add -g @papicandela/mcx-cli

# Initialize global directory (~/.mcx/)
mcx init

Requires Bun: MCX uses Bun for runtime. Install Bun if you haven't already.

Quick Start

# 1. Initialize global MCX directory
mcx init

# 2. Generate adapters from API docs
mcx gen ./api-docs.md -n myapi

# 3. Add credentials to ~/.mcx/.env

# 4. Start server
mcx serve

Directory Structure

~/.mcx/
├── adapters/           # Your adapters
│   ├── supabase.ts     # Supabase Management API
│   ├── chrome-devtools.ts  # Chrome DevTools Protocol
│   └── myapi.ts        # Generated from OpenAPI
├── skills/             # Reusable skills
├── mcx.config.ts       # Auto-loads all adapters
├── .env                # API credentials
└── package.json        # Dependencies

# Runtime (created automatically)
~/.mcx/
├── logs/               # Server logs (mcx logs to view)
└── .cache/             # FTS5 search index

Claude Code Integration

Add to your Claude Code settings (~/.claude.json or project's .mcp.json):

{
  "mcpServers": {
    "mcx": {
      "command": "mcx",
      "args": ["serve"]
    }
  }
}

That's it! MCX automatically uses ~/.mcx/ for config and adapters.

Key Features

Feature	Description
Lazy Loading	Adapters from `~/.mcx/adapters/` metadata-scanned at startup, fully loaded on first use
Domain Hints	Adapters grouped by domain (payments, database, email, etc.) for better discoverability
Context Efficiency	Filtering happens in sandbox, model sees results only
Variable Persistence	Store results as `$invoices`, `$customers` for later use
FTS5 Search	Auto-index large outputs, search with `intent` parameter
Batch Operations	`mcx_batch` for multiple operations in one call
File Processing	`mcx_file` to process local files with `$file` injection
URL Fetching	`mcx_fetch` with HTML-to-markdown conversion
Control Flow	Loops, conditionals, retries run as native code
Privacy	Intermediate data stays in sandbox
Security	Network isolation, path traversal protection, env injection prevention

MCP Tools

Tool	Description
`mcx_execute`	Execute code with adapter access, auto-stores as `$result`
`mcx_search`	3 modes: spec exploration, FTS5 search, adapter/method search
`mcx_batch`	Multiple executions/searches in one call (bypasses throttling)
`mcx_file`	Process local files with `$file` variable injection
`mcx_fetch`	Fetch URLs with HTML-to-markdown and auto-indexing
`mcx_list`	List available adapters and skills
`mcx_stats`	Session statistics (indexed content, variables)
`mcx_run_skill`	Run a registered skill

CLI Commands

Command	Description
`mcx serve`	Start MCP server (default)
`mcx gen`	Generate adapters from OpenAPI specs (with TUI)
`mcx init`	Initialize global `~/.mcx/` directory
`mcx update`	Update CLI and global installation
`mcx list`	List available adapters and skills
`mcx run`	Run a skill directly
`mcx logs`	View server logs

See CLI documentation for details.

Included Adapters

Adapter	Methods	Description
`supabase`	24	Supabase Management API (projects, tables, functions, secrets)
`chrome-devtools`	25	Chrome DevTools Protocol (screenshots, navigation, DOM)

Generate your own adapters from OpenAPI docs:

mcx gen ./api-docs.md -n myapi

Built-in Helpers

Functions available in the sandbox:

pick(data, ['id', 'name'])     // Extract fields
first(data, 5)                  // First N items
sum(data, 'amount')             // Sum numeric field
count(data, 'status')           // Count by field
table(data, 10)                 // Markdown table

Documentation

CLI Commands - Detailed command reference
Adapters - Creating and generating adapters
Skills - Reusable operations
Configuration - Config file reference
Programmatic API - Using MCX in code
Security - Sandbox security layers

Development

git clone https://github.com/schizoidcock/mcx
cd mcx
bun install
bun run build

License

MIT

MCX (Modular Code Execution)