Chapter 2 of 15 10 min beginner

Official vs Community Server

Unity AI Relay or MCP for Unity

Verified against a working setup on 2026-08-10

Both servers below were installed and running on the same machine when this was written: Unity 6000.3.14f1, Unity AI Relay 1.0.12-build.97, and mcpforunityserver 10.0.0 on Windows 11. Versions move quickly — check dates before trusting any guide on this topic, including this one.

If you have read two Unity MCP tutorials and their instructions did not match, this is why. There are two separate projects with the same nickname.

The short version

At a glance

Aspect	Unity AI Relay	MCP for Unity
`Who ships it`	`Unity`	`Open source community`
`Unity version`	`Unity 6.3+`	`Unity 2021+`
`Install`	`AI Assistant package`	`Package + Python server`
`Server runtime`	`Bundled binary`	`Python via uv/uvx`
`Setup effort`	`Low`	`Medium`
`Tool surface`	`Very broad`	`Focused on core editing`
`Account needed`	`Unity account`	`None`

The official path: Unity AI Relay

From Unity 6.3, the com.unity.ai.assistant package ships a relay binary that speaks MCP. On Windows it lands at %USERPROFILE%\.unity\relay\relay_win.exe and is launched with a single --mcp flag.

  
 The whole config
json 
{
  "unity-mcp": {
    "command": "C:\\Users\\you\\.unity\\relay\\relay_win.exe",
    "args": ["--mcp"],
    "env": {}
  }
}
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What stands out in use is the breadth. Beyond the expected scene and script tools, the relay exposes things no community server offers:

Profiler access — frame timing samples, GC allocation summaries, counter tables. The model can read an actual profile rather than guess at performance.
Scene view and camera capture — it can render the scene to an image, including multi-angle captures.
Asset generation — materials, textures, sprite conversion, animation clips.
Shader and menu item management, package manager queries, and project-wide search.

Profiler access is the genuinely novel one. "Why does this scene drop frames?" becomes a question the model can investigate with data instead of generic advice about draw calls.

The community path: MCP for Unity

The community server predates Unity's and remains the only option below Unity 6.3. It is a Python package run through uvx, paired with a Unity package that opens a local socket.

  
 Typical config
json 
{
  "unityMCP": {
    "type": "stdio",
    "command": "C:\\Users\\you\\.local\\bin\\uvx.exe",
    "args": [
      "--from", "mcpforunityserver==10.0.0",
      "mcp-for-unity",
      "--transport", "stdio"
    ]
  }
}
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Its tool surface is narrower and squarely aimed at the everyday loop: manage scripts, manage GameObjects, manage scenes, read the console, run menu items. For most day-to-day work that is genuinely all you need.

Pinning the version with ==10.0.0 is worth doing. uvx will happily fetch a newer release otherwise, and a server that changes under you mid-project is not a fun debugging session.

The mistake I made, so you can avoid it

While checking this setup I found the community server configured in all four of my clients — Claude Code, Claude Desktop, Cursor, and VS Code — while no Unity project on the machine had its Unity-side package installed.

Every client reported the server as connected, because the Python process starts fine on its own. It simply had no Editor to talk to. Four green ticks, zero working tools.

The client connecting to the server proves nothing. Always verify end to end by asking the model to read something only your open project could know — a scene name, a console message, an asset count.

Which should you use?

If you	Use	Why
`Are on Unity 6.3 or newer`	`Official relay`	Already there, one line of config.
`Are on Unity 2021–6.2`	`Community server`	The official one does not exist for you.
`Want profiler or capture tools`	`Official relay`	The community server has no equivalent.
`Cannot use a Unity account`	`Community server`	No sign-in involved.
`Want to read the source`	`Community server`	Fully open source.
`Are just trying it out`	`Official relay`	Lowest effort to a working setup.

Do not run both against the same project at once. Two servers issuing Editor commands will interleave writes, and you will get corrupted scene edits that are genuinely hard to untangle. Pick one and disable the other in your client config.

What to take away

Unity 6.3+ ships an official MCP relay in com.unity.ai.assistant.
The community server is the only option below 6.3, and is fully open source.
The official relay has a much wider tool surface, including profiler and capture.
A connected client proves nothing — verify the Unity side end to end.
Never run both servers against one project simultaneously.