Unity MCP Compatibility: Supported Unity Versions from 2021.3 LTS to 6.x

Unity MCP supports Unity 2021.3 LTS and newer, including all Unity 6.x LTS releases, with the minimum tested version set at 2021.3.45f2.

The Unity MCP (Model Context Protocol) package by CoplayDev enables AI assistants to communicate directly with the Unity Editor through the MCP specification. Understanding which Unity versions are compatible ensures stable integration whether you are maintaining legacy projects or working with the latest Unity 6 release.

Minimum Unity Version Requirements

Unity MCP maintains strict version boundaries to ensure API compatibility and testing coverage. The repository defines a minimum Unity version floor that represents the oldest supported Long-Term Support (LTS) release.

Package Manifest Declaration

In MCPForUnity/package.json, the package explicitly declares its Unity dependency:

{
  "name": "com.coplaydev.unity-mcp",
  "version": "10.0.1-beta.6",
  "unity": "2021.3",
  "description": "Bridge that connects AI assistants to Unity via MCP"
}

The "unity": "2021.3" field establishes the baseline requirement. Any Unity editor version older than 2021.3 LTS will not load the package.

CI and Testing Floor Version

While the manifest accepts any 2021.3.x patch, the continuous integration (CI) system specifically tests against 2021.3.45f2 as the compatibility floor. This version is defined in tools/unity-versions.json with the role "floor", ensuring that the oldest supported LTS release remains functional.

Supported Unity LTS Releases

Unity MCP tracks multiple LTS streams to support both stable production environments and newer development targets. The repository maintains a single source of truth in tools/unity-versions.json that lists exact patch versions for CI and local testing.

Unity 2021.3 LTS (Compatibility Floor)

The minimum supported version is 2021.3.45f2, designated as the "floor" role in the version configuration. This represents the oldest LTS release that receives active testing and bug fix support.

Unity 2022.3 LTS

For projects requiring newer features while maintaining LTS stability, Unity MCP supports 2022.3.62f1. This version is tagged with the "lts" role in tools/unity-versions.json and receives regular CI validation.

Unity 6.x LTS (6000.x)

Unity MCP fully supports the Unity 6.x lifecycle, including:

• 6000.0.75f1 (Unity 6.0 LTS) — labeled "lts" in the configuration
• 6000.4.8f1 (Latest 6.x rolling release) — labeled "rolling" for testing against the most recent 6.x features

According to the README.md, the compatibility range explicitly extends "2021.3 LTS → 6.x", while Server/README.md confirms "Unity Editor: 2021.3 LTS or newer".

Version Configuration Examples

When setting up Unity MCP in your project, reference these configuration patterns to ensure version alignment.

Declaring Unity Version in Package Manifest

Your Unity project's Packages/manifest.json or package-specific package.json should respect the minimum version constraint:

{
  "name": "com.coplaydev.unity-mcp",
  "version": "10.0.1-beta.6",
  "unity": "2021.3",
  "description": "Bridge that connects AI assistants to Unity via MCP"
}

Setting Project Unity Version

In your Unity project's ProjectSettings/ProjectVersion.txt, specify a compatible editor version:

m_EditorVersion: 2022.3.62f1
m_EditorVersionWithRevision: 2022.3.62f1 (c8d226a9b3c6)

Running Local Tests Against Specific Versions

Use the local test harness to validate against specific Unity installations:

python tools/local_harness.py \
  --unity-version 6000.0.75f1 \
  --project-path TestProjects/UnityMCPTests

The harness reads the version list from tools/unity-versions.json to ensure the specified editor matches the supported CI matrix.

How Unity Version Compatibility is Verified

The repository centralizes version management in tools/unity-versions.json. This file acts as the canonical reference for CI pipelines and local development tools, defining exact patch versions for each support tier:

• Floor: Oldest supported LTS (2021.3.45f2)
• LTS: Current Long-Term Support releases (2022.3.62f1, 6000.0.75f1)
• Rolling: Latest 6.x release for forward compatibility testing (6000.4.8f1)

This configuration ensures that Unity MCP remains functional across the entire supported version spectrum while providing clear upgrade paths for production projects.

Summary

• Unity MCP requires Unity 2021.3 LTS or newer, with hardcoded support extending through Unity 6.x.
• The absolute minimum version tested is 2021.3.45f2, defined as the "floor" in tools/unity-versions.json.
• Supported LTS releases include 2022.3.62f1 and 6000.0.75f1 (Unity 6.0 LTS).
• The MCPForUnity/package.json manifest declares "unity": "2021.3" as the dependency baseline.
• CI and local tools reference tools/unity-versions.json as the single source of truth for exact patch versions.

Frequently Asked Questions

What is the minimum Unity version required for Unity MCP?

The minimum Unity version is 2021.3 LTS, specifically patch 2021.3.45f2 for CI verification. The MCPForUnity/package.json manifest declares "unity": "2021.3", which prevents the package from loading in older Unity editors. While any 2021.3.x patch should function, 2021.3.45f2 represents the oldest tested and supported LTS release.

Does Unity MCP support Unity 6?

Yes, Unity MCP fully supports Unity 6.x LTS releases. The repository tests against 6000.0.75f1 (Unity 6.0 LTS) and tracks the latest 6.x rolling release (6000.4.8f1) for forward compatibility. The README.md explicitly states compatibility from "2021.3 LTS → 6.x", confirming Unity 6 support.

Where is the Unity version compatibility defined in the repository?

Version compatibility is defined in three key locations:

1. MCPForUnity/package.json — Sets the minimum acceptable version ("unity": "2021.3")
2. tools/unity-versions.json — Lists exact patch versions for CI testing (floor, LTS, and rolling releases)
3. README.md and Server/README.md — Document the supported range for end users

The tools/unity-versions.json file serves as the single source of truth for automation and local testing tools.

Can I use Unity MCP with Unity 2020.3 LTS?

No, Unity MCP does not support Unity 2020.3 LTS or any version older than 2021.3. The package manifest in MCPForUnity/package.json explicitly requires "unity": "2021.3", and the CI system only tests versions from 2021.3.45f2 onward. Attempting to install the package in Unity 2020.3 will result in a compatibility error from the Unity Package Manager.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}