Doc update and duplicate check for LoadSceneAdditive

Author: Scriptwonder

.claude/skills/unity-mcp-skill/references/tools-reference.md

@@ -352,6 +352,11 @@ manage_components(
 # - "Assets/Prefabs/My.prefab" → String shorthand for asset paths
 # - "ObjectName"               → String shorthand for scene name lookup
 # - 12345                      → Integer shorthand for instanceID
+#
+# Sprite sub-asset references (for SpriteRenderer.sprite, Image.sprite, etc.):
+# - {"guid": "...", "spriteName": "SubSprite"}  → Sprite sub-asset from atlas
+# - {"guid": "...", "fileID": 12345}             → Sub-asset by fileID
+# Single-sprite textures auto-resolve from guid/path alone.
 ```
 
 ---
@@ -543,6 +548,24 @@ manage_prefabs(
     position=[0, 1, 0],
     components_to_add=["AudioSource"]
 )
+
+# Add child GameObjects to a prefab (single or batch)
+manage_prefabs(
+    action="modify_contents",
+    prefab_path="Assets/Prefabs/Player.prefab",
+    create_child=[
+        {"name": "Child1", "primitive_type": "Sphere", "position": [1, 0, 0]},
+        {"name": "Child2", "primitive_type": "Cube", "parent": "Child1"}
+    ]
+)
+
+# Add a nested prefab instance inside a prefab
+manage_prefabs(
+    action="modify_contents",
+    prefab_path="Assets/Prefabs/Player.prefab",
+    create_child={"name": "Bullet", "source_prefab_path": "Assets/Prefabs/Bullet.prefab", "position": [0, 2, 0]}
+)
+# source_prefab_path and primitive_type are mutually exclusive
 ```
 
 ---

MCPForUnity/Editor/Tools/ManageScene.cs

@@ -1516,6 +1516,10 @@ private static object LoadSceneAdditive(string scenePath)
             if (!File.Exists(Path.Combine(projectRoot, scenePath)))
                 return new ErrorResponse($"Scene not found: '{scenePath}'");
 
+            var existing = SceneManager.GetSceneByPath(scenePath);
+            if (existing.IsValid() && existing.isLoaded)
+                return new ErrorResponse($"Scene '{existing.name}' is already loaded.");
+
             var scene = EditorSceneManager.OpenScene(scenePath, OpenSceneMode.Additive);
             return new SuccessResponse($"Opened '{scene.name}' additively.", new
             {

Server/src/cli/commands/scene.py

@@ -6,7 +6,7 @@
 from typing import Optional, Any
 
 from cli.utils.config import get_config
-from cli.utils.output import format_output, print_error, print_success
+from cli.utils.output import format_output, print_error, print_success, print_warning
 from cli.utils.connection import run_command, handle_unity_errors
 
 
@@ -346,5 +346,7 @@ def validate(repair: bool):
             print_success("Scene is clean")
         elif repaired > 0:
             print_success(f"Found {total} issue(s), repaired {repaired}")
+        else:
+            print_warning(f"Found {total} issue(s), none repaired")