Update warning message for Camera Capture (#661)

MCPForUnity/Editor/Tools/ManageScene.cs

@@ -361,6 +361,41 @@ namespace MCPForUnity.Editor.Tools
             {
                 int resolvedSuperSize = (superSize.HasValue && superSize.Value > 0) ? superSize.Value : 1;
 
+                // Batch mode warning
+                if (Application.isBatchMode)
+                {
+                    McpLog.Warn("[ManageScene] Screenshot capture in batch mode uses camera-based fallback. Results may vary.");
+                }
+
+                // Check Screen Capture module availability and warn if not available
+                bool screenCaptureAvailable = ScreenshotUtility.IsScreenCaptureModuleAvailable;
+                bool hasCameraFallback = Camera.main != null || UnityEngine.Object.FindObjectsOfType<Camera>().Length > 0;
+
+#if UNITY_2022_1_OR_NEWER
+                if (!screenCaptureAvailable && !hasCameraFallback)
+                {
+                    return new ErrorResponse(
+                        "Cannot capture screenshot. The Screen Capture module is not enabled and no Camera was found in the scene. " +
+                        "Please either: (1) Enable the Screen Capture module: Window > Package Manager > Built-in > Screen Capture > Enable, " +
+                        "or (2) Add a Camera to your scene for camera-based fallback capture."
+                    );
+                }
+                
+                if (!screenCaptureAvailable)
+                {
+                    McpLog.Warn("[ManageScene] Screen Capture module not enabled. Using camera-based fallback. " +
+                        "For best results, enable it: Window > Package Manager > Built-in > Screen Capture > Enable.");
+                }
+#else
+                if (!hasCameraFallback)
+                {
+                    return new ErrorResponse(
+                        "No camera found in the scene. Screenshot capture on Unity versions before 2022.1 requires a Camera in the scene. " +
+                        "Please add a Camera to your scene or upgrade to Unity 2022.1+ for ScreenCapture API support."
+                    );
+                }
+#endif
+
                 // Best-effort: ensure Game View exists and repaints before capture.
                 if (!Application.isBatchMode)
                 {

MCPForUnity/Runtime/Helpers/ScreenshotUtility.cs

@@ -31,6 +31,34 @@ namespace MCPForUnity.Runtime.Helpers
     {
         private const string ScreenshotsFolderName = "Screenshots";
         private static bool s_loggedLegacyScreenCaptureFallback;
+        private static bool? s_screenCaptureModuleAvailable;
+
+        /// <summary>
+        /// Checks if the Screen Capture module (com.unity.modules.screencapture) is enabled.
+        /// This module can be disabled in Package Manager > Built-in, which removes the ScreenCapture class.
+        /// </summary>
+        public static bool IsScreenCaptureModuleAvailable
+        {
+            get
+            {
+                if (!s_screenCaptureModuleAvailable.HasValue)
+                {
+                    // Check if ScreenCapture type exists (module might be disabled)
+                    s_screenCaptureModuleAvailable = Type.GetType("UnityEngine.ScreenCapture, UnityEngine.ScreenCaptureModule") != null
+                        || Type.GetType("UnityEngine.ScreenCapture, UnityEngine.CoreModule") != null;
+                }
+                return s_screenCaptureModuleAvailable.Value;
+            }
+        }
+
+        /// <summary>
+        /// Error message to display when Screen Capture module is not available.
+        /// </summary>
+        public const string ScreenCaptureModuleNotAvailableError =
+            "The Screen Capture module (com.unity.modules.screencapture) is not enabled. " +
+            "To use screenshot capture with ScreenCapture API, please enable it in Unity: " +
+            "Window > Package Manager > Built-in > Screen Capture > Enable. " +
+            "Alternatively, MCP for Unity will use camera-based capture as a fallback if a Camera exists in the scene.";
 
         private static Camera FindAvailableCamera()
         {
@@ -55,24 +83,46 @@ namespace MCPForUnity.Runtime.Helpers
         public static ScreenshotCaptureResult CaptureToAssetsFolder(string fileName = null, int superSize = 1, bool ensureUniqueFileName = true)
         {
 #if UNITY_2022_1_OR_NEWER
+            // Check if Screen Capture module is available (can be disabled in Package Manager > Built-in)
+            if (IsScreenCaptureModuleAvailable)
+            {
                 ScreenshotCaptureResult result = PrepareCaptureResult(fileName, superSize, ensureUniqueFileName, isAsync: true);
                 ScreenCapture.CaptureScreenshot(result.AssetsRelativePath, result.SuperSize);
                 return result;
+            }
+            else
+            {
+                // Module disabled - try camera fallback
+                Debug.LogWarning("[MCP for Unity] " + ScreenCaptureModuleNotAvailableError);
+                return CaptureWithCameraFallback(fileName, superSize, ensureUniqueFileName);
+            }
 #else
+            // Unity < 2022.1 - always use camera fallback
+            return CaptureWithCameraFallback(fileName, superSize, ensureUniqueFileName);
+#endif
+        }
+
+        private static ScreenshotCaptureResult CaptureWithCameraFallback(string fileName, int superSize, bool ensureUniqueFileName)
+        {
             if (!s_loggedLegacyScreenCaptureFallback)
             {
-                Debug.Log("ScreenCapture is supported after Unity 2022.1. Using camera capture as fallback.");
+                Debug.Log("[MCP for Unity] Using camera-based screenshot capture. " +
+                    "This requires a Camera in the scene. For best results on Unity 2022.1+, ensure the Screen Capture module is enabled: " +
+                    "Window > Package Manager > Built-in > Screen Capture > Enable.");
                 s_loggedLegacyScreenCaptureFallback = true;
             }
 
             var cam = FindAvailableCamera();
             if (cam == null)
             {
-                throw new InvalidOperationException("No camera found to capture screenshot.");
+                throw new InvalidOperationException(
+                    "No camera found to capture screenshot. Camera-based capture requires a Camera in the scene. " +
+                    "Either add a Camera to your scene, or enable the Screen Capture module: " +
+                    "Window > Package Manager > Built-in > Screen Capture > Enable."
+                );
             }
 
             return CaptureFromCameraToAssetsFolder(cam, fileName, superSize, ensureUniqueFileName);
-#endif
         }
 
         /// <summary>