unity-mcp/Server
Bryan Thompson 9d5a817540
feat: Add tool annotations for improved LLM tool understanding (#480)
* feat: Add tool annotations for improved LLM tool understanding

Add readOnlyHint and destructiveHint annotations to all 23 tools
to help LLMs better understand tool behavior and make safer decisions.

Changes:
- Added readOnlyHint: true to 5 read-only tools:
  - debug_request_context, find_in_file, validate_script,
    manage_script_capabilities, get_sha
- Added destructiveHint: true to 18 tools that modify data:
  - All CRUD tools, execution tools, and state-modifying tools
- Added title annotations for human-readable display
- Imported ToolAnnotations from mcp.types in all tool files

This improves tool safety metadata for MCP clients.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* docs: Clarify dual-purpose tool behavior in annotations

Address Sourcery AI review feedback by updating descriptions for
batch_execute and manage_* tools to clarify their safety characteristics
depend on the specific actions/operations being performed.

Updated tools:
- batch_execute: clarifies safety depends on contained tools
- read_console: clarifies 'get' is read-only, 'clear' is destructive
- manage_asset: lists read-only vs destructive actions
- manage_gameobject: lists read-only vs destructive actions
- manage_scene: lists read-only vs destructive actions
- manage_editor: lists read-only vs destructive actions
- manage_material: lists read-only vs destructive actions
- manage_shader: lists read-only vs destructive actions
- manage_script: lists read-only vs destructive actions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: Remove destructiveHint from mixed-behavior tools

Address maintainer feedback on annotation semantics. Tools that
have both read-only and modifying actions based on the 'action'
parameter should not be marked as destructive.

Changed to title-only annotations:
- manage_gameobject (find/get vs create/modify/delete)
- manage_scene (get_hierarchy vs create/load/save)
- manage_prefabs (open_stage vs save/create)
- manage_material (ping/get vs create/set)
- manage_shader (read vs create/update/delete)
- manage_editor (telemetry_status vs play/pause)
- manage_script router (read vs create/delete)
- batch_execute (depends on contained operations)
- execute_menu_item (behavior varies by menu item)
- execute_custom_tool (behavior varies by custom tool)
- read_console (get vs clear - ephemeral UI state)

Kept destructiveHint=True for always-destructive tools:
- apply_text_edits (always writes files)
- create_script (always creates files)
- delete_script (always deletes files)
- script_apply_edits (always writes files)
- run_tests (always executes tests)
- set_active_instance (always modifies session)

* fix: Remove destructiveHint from set_active_instance

set_active_instance is a session-scoped operation that switches which
Unity instance is active. It doesn't persist data and is easily reversible,
so it should not be marked as destructive.

* fix: Re-apply destructiveHint per maintainer guidance on MCP spec

Per maintainer feedback referencing MCP docs, tools should have
destructiveHint=True if they MAY perform a destructive action,
even if they also support read-only operations.

Re-applied to tools that can destroy Unity resources:
- manage_gameobject, manage_scene, manage_prefabs
- manage_material, manage_shader, manage_script
- manage_asset, batch_execute
- execute_menu_item, execute_custom_tool

Kept as-is (no destructiveHint):
- read_console (clearing is ephemeral UI state)
- set_active_instance (session toggle, not destructive)
- manage_editor (no destructive actions)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* feat: Add tool annotations to manage_scriptable_object

Per reviewer request (@dsarno), add ToolAnnotations with destructiveHint=True
to manage_scriptable_object tool since it can create/modify ScriptableObject assets.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

* feat: Add tool annotations to new async test and refresh tools

Add readOnlyHint and destructiveHint annotations to tools added
since the last commit:

- refresh_unity: destructiveHint=True (triggers asset DB refresh)
- run_tests_async: destructiveHint=True (starts test execution)
- get_test_job: readOnlyHint=True (queries job status only)

Also regenerate uv.lock after rebase.

---------

Co-authored-by: triepod-ai <noreply@github.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: triepod-ai <199543909+triepod-ai@users.noreply.github.com>
2026-01-05 16:20:34 -08:00
..
src feat: Add tool annotations for improved LLM tool understanding (#480) 2026-01-05 16:20:34 -08:00
tests fix: Multi-session UI improvements and HTTP instance recognition (#517) 2026-01-05 16:05:38 -08:00
DOCKER_OVERVIEW.md Publish to Docker Hub (#468) 2025-12-19 17:24:04 -04:00
Dockerfile HTTP Server, uvx, C# only custom tools (#375) 2025-11-24 23:21:06 -04:00
LICENSE Publish to pypi (#466) 2025-12-19 16:43:44 -04:00
README.md chore: bump version to 8.7.1 2026-01-05 01:58:40 +00:00
__init__.py Copy the MCP server to the top level (#354) 2025-10-25 00:53:53 -04:00
pyproject.toml chore: bump version to 8.7.1 2026-01-05 01:58:40 +00:00
pyrightconfig.json Copy the MCP server to the top level (#354) 2025-10-25 00:53:53 -04:00
uv.lock feat: Add tool annotations for improved LLM tool understanding (#480) 2026-01-05 16:20:34 -08:00

README.md

MCP for Unity Server

MCP python License Discord

Model Context Protocol server for Unity Editor integration. Control Unity through natural language using AI assistants like Claude, Cursor, and more.

Maintained by Coplay - This project is not affiliated with Unity Technologies.

💬 Join our community: Discord Server

Required: Install the Unity MCP Plugin to connect Unity Editor with this MCP server. You also need uvx (requires uv) to run the server.


Installation

Option 1: PyPI

Install and run directly from PyPI using uvx.

Run Server (HTTP):

uvx --from mcpforunityserver mcp-for-unity --transport http --http-url http://localhost:8080

MCP Client Configuration (HTTP):

{
  "mcpServers": {
    "UnityMCP": {
      "url": "http://localhost:8080/mcp"
    }
  }
}

MCP Client Configuration (stdio):

{
  "mcpServers": {
    "UnityMCP": {
      "command": "uvx",
      "args": [
        "--from",
        "mcpforunityserver",
        "mcp-for-unity",
        "--transport",
        "stdio"
      ]
    }
  }
}

Option 2: From GitHub Source

Use this to run the latest released version from the repository. Change the version to main to run the latest unreleased changes from the repository.

{
  "mcpServers": {
    "UnityMCP": {
      "command": "uvx",
      "args": [
        "--from",
        "git+https://github.com/CoplayDev/unity-mcp@v8.7.1#subdirectory=Server",
        "mcp-for-unity",
        "--transport",
        "stdio"
      ]
    }
  }
}

Option 3: Docker

Use Pre-built Image:

docker run -p 8080:8080 msanatan/mcp-for-unity-server:latest --transport http --http-url http://0.0.0.0:8080

Build Locally:

docker build -t unity-mcp-server .
docker run -p 8080:8080 unity-mcp-server --transport http --http-url http://0.0.0.0:8080

Configure your MCP client with "url": "http://localhost:8080/mcp".

Option 4: Local Development

For contributing or modifying the server code:

# Clone the repository
git clone https://github.com/CoplayDev/unity-mcp.git
cd unity-mcp/Server

# Run with uv
uv run src/main.py --transport stdio

Configuration

The server connects to Unity Editor automatically when both are running. No additional configuration needed.

Environment Variables:

  • DISABLE_TELEMETRY=true - Opt out of anonymous usage analytics
  • LOG_LEVEL=DEBUG - Enable detailed logging (default: INFO)

Example Prompts

Once connected, try these commands in your AI assistant:

  • "Create a 3D player controller with WASD movement"
  • "Add a rotating cube to the scene with a red material"
  • "Create a simple platformer level with obstacles"
  • "Generate a shader that creates a holographic effect"
  • "List all GameObjects in the current scene"

Documentation

For complete documentation, troubleshooting, and advanced usage:

📖 Full Documentation


Requirements

  • Python: 3.10 or newer
  • Unity Editor: 2021.3 LTS or newer
  • uv: Python package manager (Installation Guide)

License

MIT License - See LICENSE