feat: add support for Windows-only tools and enhance platform checks

tests/test_agent_tools.py

@@ -752,6 +752,23 @@ def test_tool_schemas_hide_optional_native_tools_when_mode_off(tmp_path: Path, m
     assert "list_ui_elements" not in schemas
 
 
+def test_tool_schemas_hide_windows_only_tools_on_non_windows_host(tmp_path: Path, monkeypatch) -> None:
+    agent = _build_agent(tmp_path, monkeypatch)
+    monkeypatch.setattr(agent_module.sys, "platform", "linux")
+
+    schemas = {tool["name"]: tool for tool in agent._tool_schemas()}
+
+    assert "get_active_window" not in schemas
+    assert "list_windows" not in schemas
+    assert "detect_dialog" not in schemas
+    assert "list_ui_elements" not in schemas
+
+    result = agent._dispatch_tool("get_active_window", {})
+
+    assert result["ok"] is False
+    assert result["error"] == "Tool 'get_active_window' is only available on Windows."
+
+
 def test_list_windows_returns_structured_surface_metadata(tmp_path: Path, monkeypatch) -> None:
     agent = _build_agent(tmp_path, monkeypatch)
     monkeypatch.setattr(