Unity MCP Server: Claude Code Setup, Cost and Free Options

Typing "add a spawn point and fix the null reference in my inventory script" into a terminal, then watching the Unity Editor do it, sounds like a demo trick. It is not. A Unity MCP server gives Claude Code hands inside the Editor: it can read the Console, create GameObjects, edit C# scripts and run tests without you pasting anything back and forth. What most tutorials skip is that the ground has moved. Unity deprecated the MCP server inside its own AI Assistant package, free community servers kept growing, and the real bill depends far less on the server than on the model you connect to it.

This page walks through the setup for each route, the actual cost in dollars and tokens, and the free options that hold up in daily use. Commands, versions and prices were checked in October 2026 against Unity's documentation, the project repositories and the Claude pricing page.

💡 Short answer: every Unity MCP server listed here is free. Claude Code is not, because it needs a paid Claude plan or API credit. The cheapest solid setup is a free community server plus the Claude plan you may already own.

Which Unity MCP Server Should You Pick

Four names come up in almost every search. One is official and now deprecated. Three are open source and untouched by that notice. Choosing between them comes down to your Unity version, whether you would rather have Python or Node on the machine, and how close you want to stay to Unity's own roadmap.

The Official Server and Its Deprecation

Unity ships an MCP server inside the com.unity.ai.assistant package. It needs Unity 6 (6000.0) or later and lives under Edit > Project Settings > AI > Unity MCP. The current docs open with a blunt line: "Unity MCP server is deprecated. Use the Unity command-line interface (CLI) instead."

Read the scope carefully, because it is narrower than it sounds:

The Unity CLI ships its own MCP server, built on the Unity Pipeline package, and it speaks the same protocol, so your client connects the same way it does today. Unity says this MCP mode is not part of the deprecation and "remains fully supported."

Three Community Servers Compared

MCP for Unity exposes 48 tool entrypoints for scenes, GameObjects, C# scripts, assets, tests, profiling and builds. It also works with Claude Desktop, VS Code, Cursor, Windsurf, Cline and Gemini CLI, so one install serves whichever client you try next. Unity-MCP advertises 70+ built-in tools across project and assets, scene and hierarchy, scripting and editor, and profiling. mcp-unity adds batch operations with rollback, handy when an agent touches many objects at once.

A quick rule of thumb: on Unity 2021 or 2022, pick MCP for Unity. On Unity 6 with Node already installed, mcp-unity is the simplest fit. If you want the most tools out of the box, look at Unity-MCP.

Claude Code Setup, Step by Step

Install Claude Code first if you have not: npm install -g @anthropic-ai/claude-code, then run claude --version to confirm it responds.

Route 1: Unity CLI, Unity's Own Path

This is where Unity now sends everyone, and it costs nothing. Unity states the CLI "is free and separate from Unity AI" and needs no Unity AI subscription. To drive a running Editor, the project must use Unity 6.0 LTS or later.

1. Install the Unity CLI from Unity's documentation.
2. Run unity pipeline install to add the Unity Pipeline package.
3. Run unity mcp configure claude to write the Claude Code configuration.
4. Run unity mcp configure --list to see every supported client and its status.
5. Run unity skill install <agent-name> to add Unity skills for your agent.

The local pipeline server accepts connections on localhost only, and the CLI drives a local Editor offline.

💡 Claude Code can run shell commands, so you may not need MCP at all. unity command and unity eval drive the Editor directly and, according to Unity, are faster and use fewer tokens than MCP. Keep MCP mode for harnesses that cannot run shell commands.

Still on the old in-editor server? Open Edit > Project Settings > AI > Unity MCP, check that Unity Bridge shows Running, expand Integrations, select Claude Code and press Configure. For a manual entry, point Claude Code at the relay binary with the --mcp argument: %USERPROFILE%\.unity\relay\relay_win.exe on Windows. The first connection shows a pending prompt in Unity, and you press Accept once. Unity's own page also lists an active trial or subscription to its AI tools as a prerequisite for this server.

Route 2: MCP for Unity

1. In Unity, open Window > Package Manager, press +, choose Add package from git URL and paste https://github.com/CoplayDev/unity-mcp.git?path=/MCPForUnity#main. The OpenUPM alternative is openupm add com.coplaydev.unity-mcp.
2. Install Python 3.10 or newer and uv.
3. In the Editor, go to Window > MCP for Unity and choose Configure All Detected Clients.
4. Open Claude Code in the project folder and run claude mcp list to confirm the connection.

Route 3: Coplay MCP Through uvx

Coplay publishes a separate walkthrough for Claude Code. It asks for Unity 2022 or later, Node.js with npm, and Python 3.11 or newer. Add the Unity package from https://github.com/CoplayDev/unity-plugin.git#beta, then register the server in one line:

claude mcp add --scope user --transport stdio coplay-mcp --env MCP_TOOL_TIMEOUT=720000 -- uvx --python ">=3.11" coplay-mcp-server@latest

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The MCP_TOOL_TIMEOUT=720000 value gives each tool call twelve minutes, which matters for long builds and test runs. That walkthrough lists no pricing, so check Coplay's site before you rely on it for a team.

Manual Configs for the Others

Unity-MCP registers with a single command, where the binary lives inside your project's Library folder:

claude mcp add ai-game-developer "<unityProjectPath>/Library/mcp-server/win-x64/gamedev-mcp-server.exe" port=<port> client-transport=stdio

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mcp-unity installs from https://github.com/CoderGamester/mcp-unity.git, starts from Tools > MCP Unity > Server Window, and reads a .mcp.json file in the project root:

{
  "mcpServers": {
    "mcp-unity": {
      "command": "node",
      "args": ["Library/PackageCache/com.gamelovers.mcp-unity@<hash>/Server~/build/index.js"]
    }
  }
}

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Replace <hash> with the real folder name from your package cache.

Check It Works

Run claude mcp list. A healthy entry reads like coplay-mcp: ✓ Connected. Then test the whole chain with the prompt Unity itself suggests: "Read the Unity console messages and summarize any warnings or errors." If Claude returns your actual Console contents, the bridge works.

What It Really Costs

The server is the cheap part. The model behind it sends the bill.

The Server Is Free

MCP for Unity and mcp-unity use the MIT license. Unity-MCP uses Apache-2.0. The Unity CLI is free too, and installing it does not require a Unity AI subscription. None of these charge per call, per seat or per scene.

Claude Code Plan or API

Claude Code is included in all paid Claude plans and shares that plan's usage limits, which leaves the Free plan out.

API math is easy to sanity check. A session that reads 400,000 input tokens and writes 40,000 output tokens on Sonnet 5.5 costs $0.80 plus $0.40, so $1.20. Scene hierarchies and Console dumps are what inflate the input side, so ask for narrow reads such as one scene or one script at a time.

Unity AI Credits on the Official Route

Unity's own AI product is a separate purchase. Personal users get a 14-day trial with 1,000 credits, then $10 per month unless they cancel. Pro, Enterprise and Industry seats include a monthly credit allotment that does not roll over. Unity's AI gateway lets Claude Code connect on your existing Anthropic subscription without spending Unity AI Credits, so a Claude plan plus the CLI avoids paying twice.

Free Options That Actually Work

"Free" needs a definition here. The servers are free. The model is the part you pay for, unless you already do.

Free Server, Plan You Already Own

Because MCP for Unity works with Claude Desktop, VS Code, Cursor, Windsurf, Cline and Gemini CLI, you can attach it to whichever assistant you already pay for. The MCP layer adds $0. If you have a Claude Pro plan, Claude Code is already inside it, and the whole stack costs the $20 you were spending anyway.

Open Models, With Caveats

Some MCP clients can route requests to a self-hosted open-weight model. Treat that as a weekend project, not a plug-and-play setup: tool calling is where small local models stumble, and Unity itself notes that some models do not compose command lines reliably. Test with the Console-summary prompt above before you trust one with a scene.

The Unity CLI also works with no agent at all. It installs and manages Editor versions, manages projects, runs headless builds and runs test suites, which makes it a free continuous integration tool on its own.

For the thinking side only, such as drafting a C# script or reading error text, hosted chat models on PicassoIA like GPT OSS 20B or Granite 8B Code Instruct 128K can stand in. They never touch your Editor, so you copy the code across by hand.

Fixing the Usual Connection Errors

Most failures come from a version mismatch or a path, not from Claude. Work down this list in order.

💡 Change one thing at a time and re-run the Console-summary prompt after each change. Guessing across three settings at once is how a ten-minute fix turns into an evening.

Game Art Around Your MCP Workflow

An MCP server moves objects around the Editor. It does not paint your textures or sculpt your props, so those assets come from somewhere else.

Concept Art and Textures With AI

Image models fill the gap between "I need a mossy stone wall" and a file in your Assets folder. Generate reference stills or flat texture candidates with Seedream 4.5, Qwen Image 3 or GPT Image 2, clean up flaws with PicassoIA Image Editor Pro, then import the files and ask Claude through MCP to create a material and assign it to the right objects.

Check seams before you tile anything. A single generated image is not guaranteed to repeat cleanly, so test the material on a large surface first.

Where 3D Models Fit

PicassoIA's catalog is built around image, video, audio and language models, and a search of its 3D category returned no models at the time of writing, so it will not hand you a mesh. What it can do is make the references a 3D artist or mesh tool needs, such as front, side and three-quarter views of a prop. Meanwhile Claude can block out a level with basic shapes through MCP, and you swap in real meshes as they arrive.

How to Use Sonnet 5 on PicassoIA

Claude Sonnet 5 will not drive your Editor, but it is a fast way to draft and debug C# before a script ever reaches Unity.

1. Open the Claude Sonnet 5 model page.
2. Fill the System Prompt once: "You write C# for Unity 6. Return one script per code block. No placeholders."
3. Paste the Console error and the script into Prompt. You can also attach a screenshot of the Console as the optional Image input.
4. Set Effort. The default is low, which skips extended thinking for the fastest, cheapest answer. Use high when a bug spans several scripts, and max for the stubborn ones.
5. Leave Max Tokens at the default 8,192 unless a long script gets cut off.
6. Copy the output into Unity, or paste it into Claude Code as the spec for what to build.

💡 Image input shrinks pictures to 0.5 megapixels by default. If Console text looks blurry in the answer, crop the screenshot to the error lines instead of sending the full window.

Prefer a different model? Claude Opus 4.7, Claude 4.5 Haiku and Claude Fable 5 are all in the same large language model collection.

Make Your Own Game Art

You now have a working path from a terminal sentence to a changed scene, and a clear view of what each piece costs. The missing half is the art that fills the scene.

Open Picasso IA and try it on your own project. Start with one prop you keep putting off, write a short prompt for it in Seedream 4.5, compare it with the same prompt in Qwen Image 3, and keep the one that fits your scene. Then let your Unity MCP server place it. Browse the full list at picassoia.com/en/all-models and run a few experiments before your next build.