The MSBuild Binlog Analyzer for VS Code extension is now available in preview on the Visual Studio Marketplace, bringing binary MSBuild log analysis directly into the Visual Studio Code editor instead of requiring a separate viewer. The extension uses GitHub Copilot to help developers understand the causes of build failures, analyze slowdowns, compare multiple builds, and detect regressions.
.binlog files record details about MSBuild projects, targets, tasks, properties, and diagnostics. However, extracting important information from them may require opening another tool and knowing where to look. The extension addresses this problem by turning log content into understandable answers within the development environment itself.
Analyzing Failure Causes and Performance
Developers can ask Copilot why a build failed, and the extension provides an explanation in clear language instead of requiring a manual search through NuGet package restore messages and other output. It also enables the fix to be applied with one click: Copilot reads the failed project, applies the fix, rebuilds it, and then loads the before-fix and after-fix logs to verify the result. Problems can also be fixed one at a time by right-clicking a diagnostic and selecting Auto-fix with Copilot.
When builds are slow, the extension displays the slowest targets and tasks in order, highlighting the critical path that determines the actual build duration. It can also explain which targets were rebuilt and why, helping verify that incremental builds are working instead of relying on guesswork.
Comparison and Regression Detection
Any loaded binlog file can be set as a baseline, allowing the extension to compare subsequent builds against it automatically. A status-bar badge shows the percentage change compared with the baseline, while the Regressions node displays details about the changes, including targets that became slower, added or removed diagnostics, differences in MSBuild properties, and changes in NuGet package versions.
The Build Comparison interface provides a visual comparison between two logs at the target level, showing differences and highlighting the critical path calculated by the MCP server. The source mentions an example in which Copilot traced a 473% increase to a CoreCompile operation that began from a cold state, explaining that it was the cost of the initial compilation rather than a problem with the code.
Server and Installation
The extension works together with the Microsoft.AITools.BinlogMcp .NET global tool, which exposes dozens of build-analysis tools through the Model Context Protocol. Copilot calls these tools to rely on the actual data contained in the log, and the server is installed automatically on first use without manual configuration.
To use the extension, developers need VS Code version 1.99 or later, GitHub Copilot, and the .NET SDK. A binlog file can be opened through the Binlog: Load File command in the Command Palette using the Ctrl+Shift+P shortcut, or a log can be created during the build through the Build & Collect Binlog option, or opened from Structured Log Viewer.
After loading the log, users can interact with the @binlog participant in Copilot Chat using questions such as why the build failed or which targets are slowest, along with commands such as /errors, /perf, /timeline, /compare, /summary, /incremental, and /buildcheck.
Additional Tools and CI/CD Integration
The extension includes a Binlog Explorer that displays projects, errors, warnings, and performance sections. It also shows diagnostics in VS Code's native Problems panel, with CodeLens for each project and an option to request an explanation from Copilot. Other features include a duration timeline, the ability to suggest and apply optimizations and then verify them through an automatic comparison between two tests, and search across build events, tasks, messages, and properties.
It also enables binlog files to be downloaded from Azure DevOps Pipelines and GitHub Actions, with filtering by branch or pull request, so failed CI builds can be analyzed without leaving VS Code. Language tools are available for agent mode and custom chat modes, in addition to the ready-made Build Analysis mode.
The extension is still in preview and is under active development. For those interested in working without an editor interface, the source points to the Microsoft Binlog MCP Server, which uses the same analysis engine in a headless manner, making it suitable for noninteractive investigations in CI environments. Reports and suggestions are accepted through the dotnet/skills repository.