docs(camera): clarify screenshot camera param behavior and UI capture limitation

Clarify screenshot camera param behavior and UI capture limitation

Corrects misleading "Defaults to Camera.main" in the camera parameter description

and adds explicit warnings that specifying a camera excludes Screen Space - Overlay

canvases from the capture.

Author: sssooonnnggg

Server/src/services/tools/manage_camera.py

@@ -61,7 +61,11 @@
         "- release_override: Release camera override\n"
         "- list_cameras: List all cameras with status\n\n"
         "CAPTURE:\n"
-        "- screenshot: Capture from a camera. Supports include_image=true for inline base64 PNG, "
+        "- screenshot: Capture a screenshot. By default (no camera specified) uses ScreenCapture API, "
+        "which captures all render layers including Screen Space - Overlay UI canvases. "
+        "Specifying a camera uses direct camera rendering, which EXCLUDES Screen Space - Overlay canvases "
+        "(use only when you need a specific viewpoint without UI). "
+        "Supports include_image=true for inline base64 PNG, "
         "batch='surround' for 6-angle contact sheet, batch='orbit' for configurable grid, "
         "view_target/view_position for positioned capture, and capture_source='scene_view' to capture "
         "the active Unity Scene View viewport.\n"
@@ -90,7 +94,10 @@ async def manage_camera(
     screenshot_super_size: Annotated[int | str | None,
         "Screenshot supersize multiplier (integer >= 1)."] = None,
     camera: Annotated[str | None,
-        "Camera to capture from (name, path, or instance ID). Defaults to Camera.main."] = None,
+        "Camera to capture from (name, path, or instance ID). "
+        "Omit to use ScreenCapture API (captures all layers including Screen Space Overlay UI). "
+        "Specify only when you need a particular camera viewpoint; note that Screen Space - Overlay "
+        "canvases will NOT appear in camera-rendered captures."] = None,
     include_image: Annotated[bool | str | None,
         "If true, return screenshot as inline base64 PNG. Default false."] = None,
     max_resolution: Annotated[int | str | None,