@standardbeagle/devtool-mcp

devtool-mcp

An MCP (Model Context Protocol) server that provides comprehensive development tooling capabilities to AI assistants.

Overview

devtool-mcp bridges the gap between AI assistants and development workflows by providing:

• Project Detection - Automatically detect project types (Go, Node.js, Python) and available scripts
• Process Management - Start, monitor, and control long-running processes with output capture
• Reverse Proxy - Intercept HTTP traffic with automatic frontend instrumentation
• Frontend Diagnostics - 50+ primitives for DOM inspection, layout debugging, and accessibility auditing

Documentation

Full Documentation →

Run Documentation Locally

cd docs-site
npm install
npm start

Then open http://localhost:3000/devtool-mcp/.

Deploy to GitHub Pages

Documentation is automatically deployed to GitHub Pages when changes are pushed to the main branch. You can also manually trigger deployment from the Actions tab.

To set up GitHub Pages for your fork:

• Go to repository Settings → Pages
• Set Source to "GitHub Actions"
• Push changes to trigger deployment

Quick Start

Installation

npm (recommended for Node.js users):

npm install -g @standardbeagle/devtool-mcp

pip/uv (recommended for Python users):

pip install devtool-mcp
# or
uv pip install devtool-mcp

One-liner bash install:

curl -fsSL https://raw.githubusercontent.com/standardbeagle/devtool-mcp/main/install.sh | bash

From source:

git clone https://github.com/standardbeagle/devtool-mcp.git
cd devtool-mcp
make build
make install-local

Go install:

go install github.com/standardbeagle/devtool-mcp@latest

Configuration

Add to your MCP client configuration:

{
  "mcpServers": {
    "devtool": {
      "command": "/path/to/devtool-mcp"
    }
  }
}

Usage Example

// Detect project type
detect {path: "."}
→ {type: "node", scripts: ["dev", "build", "test"]}

// Start dev server
run {script_name: "dev"}
→ {process_id: "dev", state: "running"}

// Set up debugging proxy
proxy {action: "start", id: "app", target_url: "http://localhost:3000", port: 8080}
→ {listen_addr: ":8080"}

// Debug frontend issues
proxy {action: "exec", id: "app", code: "window.__devtool.inspect('#my-button')"}
→ Full element analysis including position, styles, accessibility

Features

Project Detection

Automatically detect Go, Node.js, and Python projects with available commands:

detect {path: "."}
→ {
    type: "node",
    package_manager: "pnpm",
    scripts: ["dev", "build", "test", "lint"]
  }

Process Management

Run scripts with output capture, filtering, and graceful shutdown:

run {script_name: "test", mode: "foreground"}
→ {exit_code: 0, runtime: "12.3s"}

proc {action: "output", process_id: "test", grep: "FAIL"}
→ Filter output for failures

Reverse Proxy

Transparent HTTP proxy with traffic logging and frontend instrumentation:

proxy {action: "start", id: "debug", target_url: "http://localhost:3000", port: 8080}

// All traffic is logged
proxylog {proxy_id: "debug", types: ["http", "error"]}

// JavaScript errors are captured automatically
proxylog {proxy_id: "debug", types: ["error"]}
→ {message: "TypeError...", stack: "...", source: "main.js:142"}

Frontend Diagnostics

50+ primitives injected into all HTML pages:

window.__devtool.inspect('#element')      // Comprehensive analysis
window.__devtool.diagnoseLayout()         // Find layout issues
window.__devtool.auditAccessibility()     // A11y audit with score
window.__devtool.screenshot('bug')        // Capture screenshot
window.__devtool.highlight('.item')       // Visual debugging
window.__devtool.selectElement()          // Interactive picker

MCP Tools

Tool	Description
detect	Detect project type and available scripts
run	Execute scripts or raw commands
proc	Monitor, query output, stop processes
proxy	Manage reverse proxies
proxylog	Query traffic logs and errors
currentpage	View grouped page sessions
daemon	Manage the background daemon service

Architecture

┌─────────────────────────────────────────────────────────────┐
│                    MCP Tools Layer                           │
│  detect │ run │ proc │ proxy │ proxylog │ currentpage       │
├─────────────────────────────────────────────────────────────┤
│                  Business Logic Layer                        │
│   ProjectDetector │ ProcessManager │ ProxyManager            │
├─────────────────────────────────────────────────────────────┤
│                   Infrastructure Layer                       │
│          RingBuffer │ TrafficLogger │ PageTracker            │
└─────────────────────────────────────────────────────────────┘

Key design decisions:

• Lock-free concurrency using sync.Map and atomics
• Bounded memory with ring buffers for output capture
• Graceful shutdown with signal handling and process groups
• Zero dependencies for injected frontend JavaScript

Development

# Build
make build

# Run tests
make test

# Format and lint
make fmt
make vet
make lint

# Run with coverage
make test-coverage

Documentation Structure

docs-site/
├── docs/
│   ├── intro.md                    # Overview
│   ├── getting-started.md          # Installation & setup
│   ├── features/                   # Feature guides
│   │   ├── project-detection.md
│   │   ├── process-management.md
│   │   ├── reverse-proxy.md
│   │   └── frontend-diagnostics.md
│   ├── concepts/                   # Architecture
│   │   ├── architecture.md
│   │   ├── lock-free-design.md
│   │   └── graceful-shutdown.md
│   ├── api/                        # API reference
│   │   ├── detect.md
│   │   ├── run.md
│   │   ├── proc.md
│   │   ├── proxy.md
│   │   ├── proxylog.md
│   │   ├── currentpage.md
│   │   └── frontend/              # Frontend API (50+ functions)
│   │       ├── overview.md
│   │       ├── element-inspection.md
│   │       ├── accessibility.md
│   │       └── ...
│   └── use-cases/                  # Real-world guides
│       ├── debugging-web-apps.md
│       ├── automated-testing.md
│       ├── performance-monitoring.md
│       ├── ci-cd-integration.md
│       ├── accessibility-auditing.md
│       └── frontend-error-tracking.md

Requirements

• Go 1.24.2 or later
• MCP-compatible AI assistant (Claude Code, Cursor, etc.)

License

MIT

Contributing

Contributions welcome! Please read the documentation first to understand the architecture and design decisions.