Unity MCP

# Unity Client SynchronizationContext Fix ## Problem The Unity client shows this error when calling `ListToolsAsync`: ``` [GameSmith MCP] ListTools error: The current SynchronizationContext may not be used as a TaskScheduler. [GameSmith MCP] Server initialized with 0 tools ``` **Root Cause**: The error occurs at `MCPClientAsync.cs:285` because the code is mixing `System.Threading.Tasks.Task` with Unity's `SynchronizationContext` incorrectly. ## Verified Working The MCP server itself is **working correctly** - it has **33 tools** registered and responds properly to `tools/list` requests. The issue is purely in the Unity C# client threading code. ## Solution The `ListToolsAsync` method in `MCPClientAsync.cs` needs to be updated to properly handle async operations in Unity. ### Current Problem Pattern (causes the error) ```csharp // ❌ This causes SynchronizationContext errors in Unity var task = _process.StandardOutput.ReadLineAsync(); await task.ConfigureAwait(false); // or await Task.Run(...) ``` ### Correct Pattern for Unity ```csharp // ✅ Option 1: Use UniTask extension var line = await _process.StandardOutput.ReadLineAsync().AsUniTask(); // ✅ Option 2: Stay on Unity's main thread var line = await _process.StandardOutput.ReadLineAsync(); // (without ConfigureAwait(false) or Task.Run) // ✅ Option 3: If using Task.Run, use proper scheduling await UniTask.SwitchToThreadPool(); var result = await DoWorkAsync(); await UniTask.SwitchToMainThread(); ``` ## Specific Fix for MCPClientAsync.cs Find the `ListToolsAsync` method around line 285 and ensure: 1. **Remove `Task.Run()` or `.ConfigureAwait(false)`** from async IO operations 2. **Use `.AsUniTask()`** extension when awaiting `Task<T>` from .NET libraries 3. **Stay on the main thread** for Unity API calls ### Example Fix ```csharp public async UniTask ListToolsAsync() { try { var request = new { jsonrpc = "2.0", id = NextId++, method = "tools/list" }; var json = JsonConvert.SerializeObject(request); await _process.StandardInput.WriteLineAsync(json); // Keep on main thread await _process.StandardInput.FlushAsync(); // Use AsUniTask() to convert Task to UniTask var response = await _process.StandardOutput.ReadLineAsync().AsUniTask(); // Parse and handle response var result = JsonConvert.DeserializeObject<ToolsListResponse>(response); Debug.Log($"[GameSmith MCP] Server initialized with {result.Result.Tools.Count} tools"); } catch (Exception ex) { Debug.LogError($"[GameSmith MCP] ListTools error: {ex.Message}"); } } ``` ## Key Points 1. **Unity's SynchronizationContext is not a TaskScheduler** - You cannot use it with `Task.Run()` or certain `.ContinueWith()` patterns 2. **UniTask is designed for Unity** - Use `.AsUniTask()` when converting from `System.Threading.Tasks.Task` 3. **Avoid thread pool operations** - Unless explicitly needed, stay on Unity's main thread 4. **Never use `.ConfigureAwait(false)`** in Unity - This can cause cross-thread Unity API calls which will fail ## Testing After Fix After applying the fix, you should see: ``` [GameSmith MCP] Server initialized with 33 tools [GameSmith] MCP server connected with 33 tools ``` Instead of: ``` [GameSmith MCP] Server initialized with 0 tools [GameSmith] MCP server connected with 0 tools ``` ## Available Tools (30 total) Once fixed, the client will correctly detect all 30 tools: - setup_mcp - select_objects - transform_objects - align_objects - distribute_objects - duplicate_objects - delete_objects - find_objects - enter_play_mode - exit_play_mode - run_test - playmode_status - set_timescale - list_scenes - load_scene - save_scene - get_hierarchy - find_in_scene - cleanup_scene - get_console_logs - clear_console - create_prefab - get_assets - refresh_assets - execute_menu_item - add_package - run_tests - add_asset_to_scene - create_script - read_script - update_script - delete_script - validate_script ## References - [UniTask Documentation](https://github.com/Cysharp/UniTask) - [Unity Threading and TaskScheduler](https://docs.unity3d.com/Manual/JobSystemTroubleshooting.html) - [Async/Await in Unity](https://blog.unity.com/technology/custom-coroutines-in-unity)