mcpsafari.mp4

MCPSafari: Native Safari MCP Server for AI Agents

Give Claude, Cursor, or any MCP-compatible AI full native control of Safari on macOS. Navigate tabs, click/type/fill forms (even React), read HTML/accessibility trees, execute JS, capture screenshots, inspect console & network — all with 23 secure tools. Zero Chrome overhead, Apple Silicon optimized, token-authenticated, and built with official Swift + Manifest V3 Safari Extension.

Why MCPSafari?

• Smarter element targeting (UID + CSS + text + coords + interactive ranking)
• Works flawlessly with complex sites
• Local & private (runs on your Mac)
• Perfect drop-in for Mac-first agent workflows

macOS 14+ • Safari 17+ • Xcode 16+

Built with the official swift-sdk and a Manifest V3 Safari Web Extension.

Why Safari over Chrome?

• 40–60% less CPU/heat on Apple Silicon
• Keeps your existing Safari logins/cookies
• Native accessibility tree (better than Playwright for complex UIs)

How It Works

MCP Client (Claude, etc.)
        │ stdio
┌───────▼──────────────┐
│  Swift MCP Server    │
│  (MCPSafari binary)  │
└───────┬──────────────┘
        │ WebSocket (localhost:8089)
┌───────▼──────────────┐
│  Safari Extension    │
│  (background.js)     │
└───────┬──────────────┘
        │ content scripts
┌───────▼──────────────┐
│  Safari Browser      │
│  (macOS 14.0+)       │
└──────────────────────┘

The MCP server communicates with clients over stdio and bridges tool calls to the Safari extension over a local WebSocket. The extension executes actions via browser APIs and content scripts injected into pages.

Requirements

• macOS 14.0 (Sonoma) or later
• Safari 17+
• Swift 6.1+ (for building from source)
• Xcode 16+ (for building the Safari extension)

Installation

Homebrew (recommended)

Installs the MCP server binary and the Safari extension app to /Applications in one step. Automatically cleans up any previous installation.

brew install --cask epistates/tap/mcp-safari

Upgrading:

brew upgrade --cask epistates/tap/mcp-safari

After install, enable the extension in Safari > Settings > Extensions > MCPSafari Extension.

From Release

If you don't use Homebrew, download both the CLI binary and the extension app from GitHub Releases:

Asset	Description
MCPSafari-Server-arm64-apple-darwin	MCP server binary for Apple Silicon (M1, M2, M3, M4)
MCPSafari-Server-x86_64-apple-darwin	MCP server binary for Intel Macs
MCPSafari-Server-universal-apple-darwin	MCP server binary — universal, runs on any Mac
MCPSafari-Extension-arm64.tar.gz	Safari extension app for Apple Silicon (M1, M2, M3, M4)
MCPSafari-Extension-x86_64.tar.gz	Safari extension app for Intel Macs

# Apple Silicon (M1/M2/M3/M4) — use x86_64 for Intel Macs
curl -L -o /usr/local/bin/mcp-safari https://github.com/Epistates/MCPSafari/releases/latest/download/MCPSafari-Server-arm64-apple-darwin
chmod +x /usr/local/bin/mcp-safari

# Safari extension (must be in /Applications for macOS 26+)
curl -L https://github.com/Epistates/MCPSafari/releases/latest/download/MCPSafari-Extension-arm64.tar.gz | tar xzf -
mv MCPSafari.app /Applications/
open /Applications/MCPSafari.app

Then enable the extension in Safari > Settings > Extensions > MCPSafari Extension.

From Source

git clone https://github.com/Epistates/MCPSafari.git
cd MCPSafari

# Build the MCP server
cd MCPServer
swift build -c release
# Binary is at .build/release/MCPSafari

# Build and open the Safari extension
cd ../MCPSafari
xcodebuild -project MCPSafari.xcodeproj -scheme MCPSafari build
open ~/Library/Developer/Xcode/DerivedData/MCPSafari-*/Build/Products/Debug/MCPSafari.app

Then enable the extension in Safari > Settings > Extensions > MCPSafari Extension.

Configuration

Claude Code

Add to your MCP settings (.claude/settings.json or project-level):

{
  "mcpServers": {
    "mcp-safari": {
      "command": "mcp-safari"
    }
  }
}

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "mcp-safari": {
      "command": "mcp-safari"
    }
  }
}

Cursor / Windsurf / Other MCP Clients

Any client that supports the MCP stdio transport can connect. Point it at mcp-safari (or the full path if not in $PATH).

Multiple Claude Instances

Multiple MCP clients work automatically. The server auto-finds a free port if the default (8089) is in use, and the extension auto-discovers all servers in the 8089-8098 range. No configuration needed — just start multiple clients and they each get their own connection.

For ports outside the default range, add them manually in the extension popup or specify explicitly:

{
  "mcpServers": {
    "mcp-safari": {
      "command": "mcp-safari",
      "args": ["--port", "9090"]
    }
  }
}

CLI Options

Flag	Description
--port <n> / -p <n>	WebSocket port (default: 8089)
--verbose	Debug-level logging to stderr

Tools (23)

Tab Management

Tool	Description
tabs_context	List all open tabs with IDs, URLs, and titles
tabs_create	Open a new tab, optionally with a URL
close_tab	Close a tab by ID
select_tab	Pin a tab as the default context for future calls

Navigation

Tool	Description
navigate	Go to a URL, or use back / forward / reload actions

Page Reading

Tool	Description
read_page	Get page content as text, html, or snapshot
snapshot	Accessibility tree with element UIDs for interaction
find	Find elements by CSS selector, text, or ARIA role

Interaction

Tool	Description
click	Click by UID, CSS selector, text, or coordinates
type_text	Type into an element with optional clearFirst and submitKey
form_input	Batch fill form fields (CSS selector → value map)
select_option	Select a dropdown option by value or label
scroll	Scroll page or element in any direction
press_key	Press key combinations (e.g., Enter, Meta+a, Control+c)
hover	Hover to trigger tooltips, menus, or hover states
drag	Drag and drop between elements

Dialogs

Tool	Description
handle_dialog	Accept or dismiss alerts, confirms, and prompts

Screenshots

Tool	Description
screenshot	Capture the visible tab area as a PNG image

JavaScript

Tool	Description
javascript_tool	Execute arbitrary JS in the page context

Debugging

Tool	Description
read_console	Read console messages with level and regex filtering
read_network	Read captured XHR/fetch requests with type filtering

Window

Tool	Description
resize_window	Resize the browser window to specific dimensions

Utility

Tool	Description
wait	Wait for a duration, CSS selector, or text to appear

Usage

Basic Workflow

1. Start with context — call tabs_context to see what's open, or navigate to a URL.
2. Take a snapshot — call snapshot to get the accessibility tree with element UIDs.
3. Interact — use UIDs from the snapshot with click, type_text, hover, etc.
4. Verify — pass includeSnapshot: true on interaction tools to see the updated state, or take a screenshot.

Element Targeting

Tools that interact with elements accept multiple targeting strategies:

Strategy	Example	When to Use
UID	uid: "e42"	Most precise — from a snapshot
CSS selector	selector: "#login-btn"	When you know the DOM structure
Text	text: "Sign In"	Interactive elements are ranked higher
Coordinates	x: 100, y: 200	Last resort — click at exact position

Form Filling

Use form_input to fill multiple fields at once:

{
  "fields": {
    "#name": "Jane Doe",
    "#email": "jane@example.com",
    "textarea[name=message]": "Hello!"
  }
}

This uses React-compatible value setting (nativeInputValueSetter) so it works with controlled inputs in React, Next.js, and similar frameworks.

Smart Text Matching

When targeting by text, interactive elements (buttons, links, inputs) are ranked higher than generic containers. Clicking text: "Submit" will prefer a <button>Submit</button> over a <div>Submit</div>.

Post-Action Snapshots

Most interaction tools support includeSnapshot: true, which returns the updated accessibility tree after the action — useful for verifying the result without a separate snapshot call.

Architecture

MCP Server (MCPServer/)

A Swift executable using the official modelcontextprotocol/swift-sdk. Communicates with MCP clients via stdio and with the Safari extension via a WebSocket bridge using Network.framework.

• main.swift — Entry point, parses CLI flags, starts the server
• SafariMCPServer.swift — Tool definitions and handlers (actor)
• WebSocketBridge.swift — WebSocket server with request/response correlation (actor)
• BridgeMessage.swift — Wire protocol types and AnyCodable serialization

Safari Extension (MCPSafari/)

A Manifest V3 Safari Web Extension with:

• background.js — WebSocket client, request router, tab/navigation/screenshot handlers
• content.js — DOM interaction, accessibility snapshots, element finding, click/type/scroll simulation
• dialog-interceptor.js — Patches window.alert/confirm/prompt before page scripts run
• console-interceptor.js — Captures console messages for read_console
• network-interceptor.js — Captures XHR/fetch requests for read_network
• popup.html/js/css — Extension popup showing connection status

macOS Host App

A minimal macOS app (AppDelegate.swift, ViewController.swift) that registers the Safari extension and provides native messaging for auth token exchange.

Security

WebSocket Authentication

The server generates a random UUID token at startup, writes it to ~/.config/mcp-safari/token (mode 0600), and requires it as the first WebSocket message. The extension reads the token via native messaging from the host app. Connections without a valid token are accepted in unauthenticated mode for development convenience.

Input Validation

• URL schemes restricted to http, https, about, and file
• Navigation actions validated against an allowlist
• Regex patterns capped at 200 characters and validated before forwarding
• Wait durations capped at 300 seconds

Permissions

The extension requests these permissions in manifest.json:

Permission	Purpose
tabs	List and manage tabs
activeTab	Access the active tab
scripting	Inject content scripts and execute JS
webNavigation	Navigate tabs (back/forward/reload)
nativeMessaging	Auth token exchange with host app
alarms	Service worker keepalive
storage	Persist selected tab across suspensions

Troubleshooting

Extension shows "Disconnected"

1. Make sure the MCP server is running (check your MCP client logs)
2. Verify port 8089 is not in use: lsof -i :8089
3. Click "Reconnect" in the extension popup
4. Use --verbose flag on the server for debug logs

"Could not establish connection" errors

The content scripts may not be injected yet. The extension auto-injects on first interaction, but you can also reload the page.

Safari permission prompts

Safari prompts for per-site permissions the first time the extension interacts with a domain. Click "Always Allow on Every Website" in Safari > Settings > Extensions > MCPSafari Extension to avoid repeated prompts.

Port already in use

Use --port to pick a different port:

{
  "mcpServers": {
    "mcp-safari": {
      "command": "mcp-safari",
      "args": ["--port", "9090"]
    }
  }
}

Development

Build & Test

# Build the MCP server
cd MCPServer
swift build

# Build the Safari extension
cd MCPSafari
xcodebuild -project MCPSafari.xcodeproj -scheme MCPSafari build

# Run the server with verbose logging
.build/debug/MCPSafari --verbose

CI

The CI workflow runs on every push and PR to main:

1. Builds the MCP server (swift build)
2. Tests the MCP handshake (verifies the binary responds to initialize)
3. Builds the Safari extension (xcodebuild)

Project Structure

MCPSafari/
├── MCPServer/                      # Swift MCP server
│   ├── Package.swift
│   └── Sources/mcp-safari/
│       ├── main.swift
│       ├── SafariMCPServer.swift
│       ├── WebSocketBridge.swift
│       └── BridgeMessage.swift
├── MCPSafari/                      # Xcode project
│   ├── MCPSafari/                  # macOS host app
│   ├── MCPSafari Extension/        # Safari web extension
│   │   ├── Resources/
│   │   │   ├── background.js
│   │   │   ├── content.js
│   │   │   ├── dialog-interceptor.js
│   │   │   ├── console-interceptor.js
│   │   │   ├── network-interceptor.js
│   │   │   ├── manifest.json
│   │   │   └── popup.html/js/css
│   │   └── SafariWebExtensionHandler.swift
│   └── MCPSafari.xcodeproj
├── .github/workflows/
│   ├── ci.yml
│   └── release.yml
└── CHANGELOG.md

License

MIT