Next.js DevTools MCP

next-devtools-mcp is a Model Context Protocol (MCP) server that provides Next.js development tools and utilities for coding agents like Claude and Cursor.

Features

This MCP server provides coding agents with comprehensive Next.js development capabilities through three primary mechanisms:

1. Runtime Diagnostics & Live State Access (Next.js 16+)

Connect directly to your running Next.js dev server's built-in MCP endpoint to query:

• Real-time build and runtime errors
• Application routes, pages, and component metadata
• Development server logs and diagnostics
• Server Actions and component hierarchies

2. Development Automation

Tools for common Next.js workflows:

• Automated Next.js 16 upgrades with official codemods
• Cache Components setup with error detection and automated fixes
• Browser testing integration via Playwright for visual verification

3. Knowledge Base & Documentation

• Curated Next.js 16 knowledge base (12 focused resources on Cache Components, async APIs, etc.)
• Direct access to official Next.js documentation via search API
• Pre-configured prompts for upgrade guidance and Cache Components enablement

Learn more: See the Next.js MCP documentation for details on how MCP servers work with Next.js and coding agents.

How It Works

This package provides a bridge MCP server that connects your coding agent to Next.js development tools:

Coding Agent
      ↓
  next-devtools-mcp (this package)
      ↓
      ├─→ Next.js Dev Server MCP Endpoint (/_next/mcp) ← Runtime diagnostics
      ├─→ Playwright MCP Server ← Browser automation
      └─→ Knowledge Base & Tools ← Documentation, upgrades, setup automation

Key Architecture Points:

1. For Next.js 16+ projects: This server automatically discovers and connects to your running Next.js dev server's built-in MCP endpoint at http://localhost:PORT/_next/mcp. This gives coding agents direct access to runtime errors, routes, logs, and application state.

2. For all Next.js projects: Provides development automation tools (upgrades, Cache Components setup), documentation access, and browser testing capabilities that work independently of the runtime connection.

3. Auto-discovery: The nextjs_runtime tool scans common ports (3000, 3001, etc.) to find running Next.js servers, so you don't need to manually specify ports in most cases.

Requirements

• Node.js v20.19 or a newer latest maintenance LTS version
• npm or pnpm

Getting Started

Add the following config to your MCP client:

{
  "mcpServers": {
    "next-devtools": {
      "command": "npx",
      "args": ["-y", "next-devtools-mcp@latest"]
    }
  }
}

[!NOTE] Using next-devtools-mcp@latest ensures that your MCP client will always use the latest version of the Next.js DevTools MCP server.

MCP Client Configuration

Using Amp CLI:

amp mcp add next-devtools -- npx next-devtools-mcp@latest

Or configure manually:

Follow Amp's MCP documentation and apply the standard configuration shown above.

Use the Claude Code CLI to add the Next.js DevTools MCP server:

claude mcp add next-devtools npx next-devtools-mcp@latest

Alternatively, manually configure Claude by editing your MCP settings file and adding the configuration shown above.

Using Codex CLI:

codex mcp add next-devtools -- npx next-devtools-mcp@latest

Or configure manually:

Follow the MCP setup guide with the standard configuration format:

• Command: npx
• Arguments: -y, next-devtools-mcp@latest

Windows 11 Special Configuration:

Update .codex/config.toml with environment variables and increased startup timeout:

env = { SystemRoot="C:\\Windows", PROGRAMFILES="C:\\Program Files" }
startup_timeout_ms = 20_000

Click the button to install:

Install in Cursor

Or install manually:

Go to Cursor Settings → MCP → New MCP Server. Use the config provided above.

Using Gemini CLI:

Project-wide installation:

gemini mcp add next-devtools npx next-devtools-mcp@latest

Global installation:

gemini mcp add -s user next-devtools npx next-devtools-mcp@latest

Or configure manually:

Follow the MCP setup guide with these parameters:

• Command: npx
• Arguments: -y, next-devtools-mcp@latest

Using VS Code CLI:

code --add-mcp '{"name":"next-devtools","command":"npx","args":["-y","next-devtools-mcp@latest"]}'

Or configure manually:

Follow the official VS Code MCP server setup guide and add the Next.js DevTools server through VS Code settings.

Using Warp UI:

Navigate to Settings | AI | Manage MCP Servers and select + Add to register a new MCP server with the following configuration:

• Name: next-devtools
• Command: npx
• Arguments: -y, next-devtools-mcp@latest

Quick Start

For Next.js 16+ Projects (Recommended)

To unlock the full power of runtime diagnostics, start your Next.js dev server:

npm run dev

Next.js 16+ has MCP enabled by default at http://localhost:3000/_next/mcp (or whichever port your dev server uses). The next-devtools-mcp server will automatically discover and connect to it.

⚠️ IMPORTANT: Start every Next.js session by calling the init tool to set up proper context:

Use the init tool to set up Next.js DevTools context

This initializes the MCP context and ensures the AI assistant uses official Next.js documentation for all queries.

After initialization, try these prompts to explore runtime diagnostics:

Next Devtools, what errors are in my Next.js application?

Next Devtools, show me the structure of my routes

Next Devtools, what's in the development server logs?

Your coding agent will use the nextjs_runtime tool to query your running application's actual state.

For All Next.js Projects

You can use the development automation and documentation tools regardless of Next.js version:

Next Devtools, help me upgrade my Next.js app to version 16

Next Devtools, enable Cache Components in my Next.js app

Next Devtools, search Next.js docs for generateMetadata

💡 Pro Tip: Auto-Initialize on Every Session

To make your AI assistant automatically call the init tool at the start of every Next.js session without being asked, add this instruction to your agent's configuration file:

Add to ~/.claude/CLAUDE.md (global) or ./.claude/CLAUDE.md (project-specific):

**When starting work on a Next.js project, ALWAYS call the `init` tool from
next-devtools-mcp FIRST to set up proper context and establish documentation
requirements. Do this automatically without being asked.**

Add to .cursorrules in your project root or global Cursor settings:

When working with Next.js, always call the init tool from next-devtools-mcp
at the start of the session to establish proper context and documentation requirements.

Add to your agent's configuration file (e.g., .codex/instructions.md, agent.md, or similar):

**Next.js Initialization**: When starting work on a Next.js project, automatically
call the `init` tool from the next-devtools-mcp server FIRST. This establishes
proper context and ensures all Next.js queries use official documentation.

Why this matters:

• ✅ Ensures consistent context across all Next.js work
• ✅ Automatically establishes the documentation-first requirement
• ✅ No need to manually call init every time
• ✅ Works across all your Next.js projects

MCP Resources

Next.js 16 knowledge base resources are automatically available to your coding agent.

These resources provide comprehensive documentation split into focused sections for efficient context management:

• nextjs16://knowledge/overview - Overview and critical errors AI agents make
• nextjs16://knowledge/core-mechanics - Fundamental paradigm shift and how cacheComponents works
• nextjs16://knowledge/public-caches - Public cache mechanics with 'use cache'
• nextjs16://knowledge/private-caches - Private cache patterns with 'use cache: private'
• nextjs16://knowledge/runtime-prefetching - Runtime prefetch configuration and patterns
• nextjs16://knowledge/request-apis - Async params, searchParams, cookies, headers APIs
• nextjs16://knowledge/cache-invalidation - updateTag, revalidateTag, and refresh patterns
• nextjs16://knowledge/advanced-patterns - cacheLife, cacheTag, draft mode, and more
• nextjs16://knowledge/build-behavior - Prerendering, resume data cache, and metadata
• nextjs16://knowledge/error-patterns - Common errors and how to fix them
• nextjs16://knowledge/test-patterns - E2E patterns from 125+ test fixtures
• nextjs16://knowledge/reference - API reference, checklists, and comprehensive nuances

Resources are loaded on-demand by your coding agent, providing targeted knowledge without overwhelming the context window.

MCP Prompts

Pre-configured prompts to help with common Next.js development tasks:

• init - Initialize context for Next.js development with MCP tools and documentation requirements
• upgrade-nextjs-16 - Guide for upgrading to Next.js 16
• enable-cache-components - Enable caching for React components

MCP Tools

Initialize Next.js DevTools MCP context and establish documentation requirements.

Capabilities:

• Sets up proper context for AI assistants working with Next.js
• Establishes requirement to use nextjs_docs for ALL Next.js-related queries
• Documents all available MCP tools and their use cases
• Provides best practices for Next.js development with MCP
• Includes example workflows and quick start checklist

When to use:

• At the beginning of a Next.js development session
• To understand available tools and establish proper context
• To ensure documentation-first approach for Next.js development

Input:

• project_path (optional) - Path to Next.js project (defaults to current directory)

Output:

• Comprehensive initialization context and guidance for Next.js development with MCP tools

Search and retrieve Next.js official documentation and knowledge base.

Capabilities:

• Two-step process: 1) Search for docs by keyword to get paths, 2) Fetch full markdown content by path
• Uses official Next.js documentation search API
• Provides access to comprehensive Next.js guides, API references, and best practices
• Supports filtering by router type (App Router, Pages Router, or both)

Input:

• action (required) - Action to perform: search to find docs, get to fetch full content
• query (optional) - Required for search. Keyword search query (e.g., 'metadata', 'generateStaticParams', 'middleware')
• path (optional) - Required for get. Doc path from search results (e.g., '/docs/app/api-reference/functions/refresh')
• anchor (optional) - Optional for get. Anchor/section from search results (e.g., 'usage')
• routerType (optional) - For search only. Filter by: app, pages, or all (default: all)

Output:

• Search results with doc titles, paths, content snippets, sections, and anchors
• Full markdown content for specific documentation pages

Automate and test web applications using Playwright browser automation.

When to use:

• Verifying pages in Next.js projects (especially during upgrades or testing)
• Testing user interactions and flows
• Taking screenshots for visual verification
• Detecting runtime errors, hydration issues, and client-side problems
• Capturing browser console errors and warnings

Important: For Next.js projects, prioritize using the nextjs_runtime tool instead of browser console log forwarding. Only use browser_eval's console_messages action as a fallback when nextjs_runtime tools are not available.

Available actions:

• start - Start browser automation (automatically installs if needed)
• navigate - Navigate to a URL
• click - Click on an element
• type - Type text into an element
• fill_form - Fill multiple form fields at once
• evaluate - Execute JavaScript in browser context
• screenshot - Take a screenshot of the page
• console_messages - Get browser console messages
• close - Close the browser
• drag - Perform drag and drop
• upload_file - Upload files
• list_tools - List all available browser automation tools from the server

Input:

• action (required) - The action to perform
• browser (optional) - Browser to use: chrome, firefox, webkit, msedge (default: chrome)
• headless (optional) - Run browser in headless mode (default: true)
• Action-specific parameters (see tool description for details)

Output:

• JSON with action result, screenshots (base64), console messages, or error information

Connect to your running Next.js dev server's built-in MCP endpoint to access live application state, runtime diagnostics, and internal information.

What this tool does:

This tool acts as a bridge between your coding agent and Next.js 16's built-in MCP endpoint at /_next/mcp. It provides three key actions:

1. discover_servers: Find all running Next.js dev servers on your machine
2. list_tools: See what runtime diagnostic tools are available from Next.js
3. call_tool: Execute a specific Next.js runtime tool (e.g., get errors, query routes, fetch logs)

Available Next.js Runtime Tools (accessed via call_tool):

Once connected to a Next.js 16+ dev server, you can access these built-in tools:

• get_errors - Get current build, runtime, and type errors
• get_logs - Get path to development log file (browser console + server output)
• get_page_metadata - Query application routes, pages, and component metadata
• get_project_metadata - Get project structure, config, and dev server URL
• get_server_action_by_id - Look up Server Actions by ID to find source files

Requirements:

• Next.js 16+ (MCP enabled by default)
• Running dev server (npm run dev)

Typical workflow:

// Step 1: Discover running servers (optional - auto-discovery works in most cases)
{
  "action": "discover_servers"
}

// Step 2: List available runtime tools
{
  "action": "list_tools",
  "port": 3000  // optional if only one server is running
}

// Step 3: Call a specific tool
{
  "action": "call_tool",
  "port": 3000,
  "toolName": "get_errors"
  // args is optional and only needed if the tool requires parameters
}

Input Parameters:

• action (required) - discover_servers, list_tools, or call_tool
• port (optional) - Dev server port (auto-discovers if not provided)
• toolName (required for call_tool) - Name of the Next.js tool to invoke
• args (optional) - Arguments object for the tool (only if required by that tool)
• includeUnverified (optional) - For discover_servers: include servers even if MCP verification fails

Output:

• JSON with discovered servers, available tools list, or tool execution results

Example prompts that use this tool:

• "Next Devtools, what errors are in my Next.js app?"
• "Next Devtools, show me my application routes"
• "Next Devtools, what's in the dev server logs?"
• "Next Devtools, find the Server Action with ID xyz"

Guides through upgrading Next.js to version 16 with automated codemod execution.

Capabilities:

• Runs official Next.js codemod automatically (requires clean git state)
• Handles async API changes (params, searchParams, cookies, headers)
• Migrates configuration changes
• Updates image defaults and optimization
• Fixes parallel routes and dynamic segments
• Handles deprecated API removals
• Provides guidance for React 19 compatibility

Input:

• project_path (optional) - Path to Next.js project (defaults to current directory)

Output:

• Structured JSON with step-by-step upgrade guidance

Complete Cache Components setup and enablement for Next.js 16 with automated error detection and fixing.

Capabilities:

• Pre-flight checks (package manager, Next.js version, configuration)
• Enable Cache Components configuration
• Start dev server with MCP enabled
• Automated route verification and error detection
• Automated error fixing with intelligent boundary setup (Suspense, caching directives, static params)
• Final verification and build testing

Input:

• project_path (optional) - Path to Next.js project (defaults to current directory)

Output:

• Structured JSON with complete setup guidance and phase-by-phase instructions

Example Usage:

With Claude Code:

Next Devtools, help me enable Cache Components in my Next.js 16 app

With other agents or programmatically:

{
  "tool": "enable_cache_components",
  "args": {
    "project_path": "/path/to/project"
  }
}

Local Development

To run the MCP server locally for development:

1. Clone the repository

2. Install dependencies:

   pnpm install
   pnpm build
   

3. Configure your MCP client to use the local version:

   {
     "mcpServers": {
       "next-devtools": {
         "command": "node",
         "args": ["/absolute/path/to/next-devtools-mcp/dist/stdio.js"]
       }
     }
   }
   

   Note: Replace /absolute/path/to/next-devtools-mcp with the actual absolute path to your cloned repository.

   or manually add, e.g. with codex:

   codex mcp add next-devtools-local -- node dist/stdio.js
   

License

MIT License