Microsoft Releases WinApp CLI 0.8 with WinUI DevTools for AI Agent Inspection

Microsoft released version 0.8 of its Windows Application Development Command Line Interface (WinApp CLI) on November 10, 2026, introducing an experimental preview feature called WinUI DevTools. This update allows developers and AI agents to inspect running WinUI 3 applications directly, viewing interface component properties, layout configurations, and corresponding XAML source code locations, while also supporting real-time testing of modifications.

WinApp CLI assists developers in building, running, debugging, and packaging Windows applications via terminal or AI agents. When launching a WinUI project with the new tool, DevTools opens by default. Developers can select interface elements like buttons to view the visual tree—the hierarchical relationship between UI components—along with attributes, data bindings, and layout information. If the system identifies the source code for a component, it displays the XAML file and line number to facilitate locating areas for modification.

Beyond inspection, developers can adjust width, spacing, or colors to immediately observe changes in the running interface. However, these modifications are for testing only and are not written to the XAML source code; they revert upon application restart. WinUI DevTools supports WinUI 3 applications developed in C# and C++. The new version also provides interface annotation features, allowing AI agents to read annotations, query component properties and source code via command line, and update processing status after making changes.

In terms of performance analysis, the new version uses Windows Event Tracing (ETW) to record WinUI execution activities, helping identify time-consuming XAML parsing, layout, and rendering operations. For .NET applications, it can check if garbage collection activities coincide with interface latency. Microsoft notes that analysis results should not be directly interpreted as GPU execution time or actual frame rates.