MSBuild Binlog Analyzer for VS Code

Analyze MSBuild binary logs (.binlog) with GitHub Copilot Chat and MCP tools — right from VS Code.

Preview — This extension is under active development. Feedback welcome — please report issues at dotnet/skills.

Quick Start

1. Install this extension (requires VS Code with the GitHub Copilot Chat extension and the .NET SDK; VS Code enforces the minimum version from the extension manifest)
2. Open a .binlog — via Binlog: Load File (Ctrl+Shift+P), Build & Collect Binlog, or from Structured Log Viewer → Open in VS Code
3. Use @binlog in Copilot Chat:

@binlog why did the build fail?
@binlog what are the slowest targets?
@binlog /perf

The Microsoft.AITools.BinlogMcp server (the MCP binlog analysis tools) is auto-installed on first use.

What You Get

Build Baseline & Regressions

A build baseline is a saved .binlog snapshot that newly-loaded builds are automatically compared against, so you can spot regressions (slower targets, new errors/warnings, changed properties). If you see "No build baseline is set.", pick one of these:

Set a baseline (any one):

• Binlog Explorer → right-click a loaded .binlog → Set This Binlog as Baseline (baselines the file you right-clicked).
• Command Palette (Ctrl+Shift+P) → Binlog: Set This Binlog as Baseline — when invoked without a tree-item context, baselines the currently active binlog.

Once set, the active binlog is compared to the baseline automatically and a Build: status-bar item (bottom-left) reflects the result.

View regressions:

• Click the Build: status-bar item, or
• Command Palette → Binlog: Show Build Regressions (focuses the regression results in the Binlog Explorer).

Clear a baseline:

• Command Palette → Binlog: Clear Build Baseline, or right-click the baseline/regressions node in the explorer → Clear Build Baseline.

Tip: a typical loop is — load a known-good build and Set This Binlog as Baseline, make a change, rebuild via Build & Collect Binlog, then read the regressions that surface automatically.

Configuration

Telemetry

This extension collects usage data and sends it to Microsoft to help improve our products and services. The extension respects the telemetry.telemetryLevel setting — learn more at https://code.visualstudio.com/docs/getstarted/telemetry. To disable telemetry in VS Code, including telemetry from this extension, set:

"telemetry.telemetryLevel": "off"

What is sent. Every extension-defined event and property is enumerated in the bundled telemetry.json using the standard 1DS classification schema (classification, endPoint, purpose); the VS Code telemetry library also adds its standard common properties (including pseudonymized machine and session identifiers). At a glance:

• Feature insight — extension activation, command invocation, chat participant / slash-command usage, tree navigation, binlog-loaded count.
• Performance & reliability — MCP tool-install success/failure, build check duration, error counts. Error messages are never sent as raw text: they are hashed with HMAC-SHA256 (16-char hex) — identical to the C# Binlog MCP server's Hash — and only the error kind (exception.type, e.g. TypeError) is sent in clear. Every event also carries binlog.build_version, matching the MCP server's conventions.

What is not sent. No .binlog content, no file system paths, no source-code snippets, no Copilot Chat conversation text, no user identifiers beyond VS Code's pseudonymized machine- and session-id hashes.

Read the Microsoft privacy statement to learn more.

Development: MCP Contract

The extension vendors the Binlog MCP JSON Schemas under src/contract/schemas/ and commits generated TypeScript declarations in src/contract/.

npm run gen:contract      # regenerate src/contract/*.d.ts from vendored schemas
npm run check:contract    # regenerate and fail if generated files drift

When server schemas change, copy the new *.schema.json files into src/contract/schemas/, run npm run gen:contract, and commit both schemas and generated types.

Troubleshooting: MCP Server Installation

The extension auto-installs Microsoft.AITools.BinlogMcp via dotnet tool install -g. In corporate environments with restricted NuGet feeds, this may fail. Here are the workarounds:

1. Install with explicit feed source

dotnet tool install -g Microsoft.AITools.BinlogMcp --prerelease --add-source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json

2. Diagnose NuGet issues

dotnet nuget list source

Common problems:

• dotnet-public feed not configured — the tool is published on the dotnet-public Azure DevOps feed
• Authenticated feed requires credentials — may block access to the feed
• Package source mapping excludes the dotnet-public feed for this package

3. Verify installation

dotnet tool list -g | Select-String Microsoft.AITools.BinlogMcp
binlog-mcp --help

Related Projects

• MSBuild Structured Log Viewer — WPF viewer with secrets redaction
• Microsoft.AITools.BinlogMcp — MCP server for binlog analysis
• MSBuild Binary Log docs

License

See the bundled LICENSE.md for the Microsoft Software License Terms.

Collect diagnostic information

When you hit a problem and want to share details with us, all relevant diagnostic information lives in VS Code's Output panel. Open View → Output and switch the dropdown to one of:

Before sharing logs publicly

Output channels may contain file paths, project property values, and environment-variable values that MSBuild surfaces into the log. Before posting a log on a GitHub issue or chat:

1. Search for and redact secrets (tokens, connection strings, passwords).
2. Search-and-replace your user home directory with ~ (the extension already does this for error strings it sends as telemetry, but the on-disk Output panel still contains the raw values).
3. If you're sharing a .binlog, consider opening it in MSBuild Structured Log Viewer and using its "Redact secrets" feature first.

For private reports (security vulnerabilities or anything you'd rather not put on a public issue), follow the process in the bundled SECURITY.md.