NextJs MCP Servers | Guide

🔍 What are MCP Servers?

Next.js MCP Servers enable AI coding agents to interact directly with your app's internals and developer environment through the Model Context Protocol (MCP).

In simple terms:

MCP enables AI coding assistants to access your Next.js app's runtime state, file structure, build errors, and server actions directly - turning vague prompts into precise, context-aware code generation and debugging.

Think of it as giving your AI assistant the same real-time visibility into your app that you have as a developer.

🧠 What is the Model Context Protocol?

MCP (Model Context Protocol) is an open standard that defines how AI agents and coding assistants can talk to applications in a structured way.

Instead of "prompting" an AI assistant with vague text, MCP exposes tools and APIs that an AI can call directly to:

Inspect your project's structure
Read runtime state and logs
Fetch build errors or configuration
Generate or modify code with awareness of your app context

Think of MCP as the bridge between your Next.js app and your AI agent.

🧩 The Two Next.js MCP Servers

Next.js offers two MCP servers that work together to provide both low-level project introspection and high-level developer guidance.

Server	Type	Purpose
Next.js MCP Server (built-in)	Internal	Gives the agent direct access to your app's internals (routes, components, errors, server actions)
Next DevTools MCP (next-devtools-mcp)	External (NPM package)	Adds developer tools, codemods, best practices, and migration helpers for AI-driven workflows

You can (and should) run both simultaneously.

🧱 1. Built-In Next.js MCP Server

🔍 What it does

When you run next dev on Next.js 16 or later, a built-in MCP server automatically starts inside your dev environment.

It exposes runtime information about your app to any connected MCP-compatible agent. That includes:

Real-time app state: What's running in memory
Routes and metadata: Page routes, layouts, and component hierarchies
Logs & errors: Build, runtime, and hydration errors
Server Actions: Access and inspect server actions by ID

⚙️ Configuration

No setup needed! If you're running:

bash

You already have it. The MCP endpoint runs inside your Next.js dev server, ready for any agent that connects.

🧠 Key Tools Exposed

Tool	Description
`get_errors`	Returns all build/runtime/type errors in the dev server
`get_logs`	Streams logs and console output
`get_page_metadata`	Returns routes, component tree, and rendering info for a given page
`get_project_metadata`	Returns your overall project configuration and structure
`get_server_action_by_id`	Finds and inspects a specific Server Action by ID

🧩 Example Workflow

User: "What errors are in my app right now?"
→ Agent calls MCP tool: get_errors
→ Response: Found hydration error on /about page
→ Agent suggests fix and edits code

The agent can now read your live error state, understand the context, and generate real, targeted fixes — not guesses.

🧰 2. Next DevTools MCP (External Package)

📦 Installation

Add next-devtools-mcp to your project by defining it in .mcp.json:

json

This tells your agent that next-devtools-mcp is available as an MCP server it can connect to.

💡 What it adds

next-devtools-mcp gives your agent higher-level powers:

Query Next.js documentation and best practices
Automate migration to Next.js 16 (codemods, route updates, etc.)
Provide guided setup for features like cacheComponents or PPR
Integrate with browser testing via Playwright MCP

🧠 Example Capabilities

Task	Action
"Help me migrate to Next.js 16"	Runs automated migration checks, applies codemods, and gives step-by-step upgrade guidance
"Explain when to use `use client`"	Queries the Next.js knowledge base and responds with docs + context from your repo
"Configure cacheComponents"	Analyzes your config and applies caching recommendations

🧬 3. How Agents Use MCP Servers

When both servers are active, your coding agent (like ChatGPT, Claude, or Cursor AI) can:

Discover running MCP servers automatically
Connect to your Next.js dev server
Call available tools programmatically (get_errors, get_logs, etc.)
Cross-reference with Next DevTools MCP to provide advice, fixes, or explanations

Example Workflow

Agent: "Let's debug your app."

🔍 Discovers local MCP servers
🔌 Connects to nextjs_runtime
🐛 Calls get_errors
📖 Reads error stack
📚 Queries docs from next-devtools-mcp
🔧 Suggests code fix + commits changes

You just watch it fix your app intelligently — no manual prompting!

🧭 4. Benefits for Developers

Feature	Description
🧩 Deep Context Awareness	Agents see your actual file tree, routes, and components
🪄 Live Diagnostics	Detect errors, logs, and misconfigurations in real time
🔄 Smart Upgrades	Automate migrations with codemods and upgrade guides
🧠 Better Code Generation	AI agents produce code aligned with your patterns and architecture
🧑‍💻 Streamlined Workflow	No need to copy-paste logs into chat — the agent reads them directly

🧪 5. Using MCP in Development

🚀 Getting Started

Run your dev server:

bash

Connect your coding agent:

Open your agent (e.g., ChatGPT with MCP support, Cursor, Claude Desktop) — it should auto-discover the running Next.js MCP server.

💬 Query Examples

Try asking your agent:

"What are the build errors right now?"
"List all routes and their components."
"What's the cache policy for my /dashboard page?"
"Migrate my project to Next.js 16."

Behind the scenes, the agent uses the MCP protocol to call your Next.js tools directly.

🧩 6. Debugging & Troubleshooting

🔌 MCP Server Not Connecting?

Ensure you're on Next.js 16+
Restart your server: npm run dev
Check .mcp.json config paths
Restart your MCP client or coding agent

🧱 Still Not Working?

Run this to verify active servers:

bash

You should see both:

✅ nextjs_runtime (built-in)
✅ next-devtools-mcp (external)

🧭 7. Best Practices & Tips

✅ Run both MCP servers — low-level + high-level complement each other
✅ Use in dev only — MCP exposes internal APIs and should never be deployed in production
✅ Keep next-devtools-mcp updated — it evolves alongside Next.js
✅ Leverage Playwright MCP for E2E AI-assisted testing
✅ Use descriptive commit messages — AI can reference git history when generating context-aware updates

🧠 Quick Summary

Component	Description
Built-in MCP Server	Exposes your app's live runtime internals
Next DevTools MCP	Provides Next.js knowledge, codemods, and best practices
Together	Give your AI assistant the same context a human engineer would have when debugging or building

🚀 Example End-to-End Flow

Scenario: You ask your agent — "Fix all hydration errors in my app."

🔍 Agent calls discover_servers
🔌 Connects to built-in nextjs_runtime
🐛 Executes get_errors
🔍 Detects hydration mismatch on /about
📚 Fetches remediation guidance from next-devtools-mcp
🔧 Edits component logic to fix render mismatch
▶️ Runs npm run dev again to verify
✅ Confirms "No runtime errors found ✅"

All automated — zero manual debugging!

🏁 Conclusion

Next.js MCP servers mark the beginning of AI-native development. Instead of building apps for humans and debugging with tools, you now build alongside agents that see, understand, and interact with your live codebase.

In short:

The built-in MCP server gives visibility into your running app
Next DevTools MCP gives intelligence to act on that visibility
Together, they turn your Next.js dev server into a real-time collaborative API for agents

Ready to supercharge your Next.js development workflow? Start with npm run dev and connect your AI assistant! 🚀