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Official agent skill

Binlog Failure Analysis

by microsoft in microsoft/testfx

Analyze MSBuild binary logs to diagnose build failures. An agent skill from microsoft/testfx.

OfficialMITAuto-check passedDevelopment

Install Binlog Failure Analysis

skills CLI
$ npx skills add microsoft/testfx --skill binlog-failure-analysis -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install microsoft/testfx binlog-failure-analysis --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/microsoft/testfx.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/binlog-failure-analysis .claude/skills/binlog-failure-analysis && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
binlog-failure-analysis
GitHub stars
1k
Used in
3 other repos
Token cost
~730 tokens
SKILL.md length
297 words
Files
1
Skills in repo
44
Repo updated
First seen
Licence
MIT

At a glance

Analyze MSBuild binary logs to diagnose build failures. An agent skill from microsoft/testfx.

  • : build errors that are unclear from console output
  • SKILL.md covers Primary workflow — binlog MCP, Fallback workflow — text-log… and Generating a binlog (only if…
  • Calls dotnet
  • Diagnosing cascading failures across multi-project builds

What it does

Binlog Failure Analysis is an agent skill from microsoft/testfx, published by the product's own GitHub organization. Analyze MSBuild binary logs to diagnose build failures. USE FOR: build errors that are unclear from console output, diagnosing cascading failures across multi-project builds, tracing MSBuild target execution order, and generally any MSBuild build issues. Requires an existing .binlog file. DO NOT USE FOR: generating binlogs (use binlog-generation), non-MSBuild build systems.

Its SKILL.md is about 730 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development, covering Root cause analysis. It works with Model Context Protocol. The repository describes itself as: This repository holds the source code of Microsoft.Testing.Platform (MTP), a lightweight alternative to VSTest, as well as MSTest adapter and framework. The licence is MIT.

When your agent uses it

  • : build errors that are unclear from console output
  • Diagnosing cascading failures across multi-project builds
  • Tracing MSBuild target execution order
  • Generally any MSBuild build issues

Example prompts

  • “/binlog-failure-analysis”

What it can do on your machine

Read from SKILL.md and the folder at commit 44b9dcc. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • dotnet

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Binlog Failure Analysis loads about 730 tokens when it runs. Until then it costs about 100 tokens; SKILL.md has 297 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~100
When it runs · the whole SKILL.md, loaded when a task matches
~730

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from microsoft/testfx at commit 44b9dcc, republished under its MIT licence (© microsoft). 297 words, ~730 tokens.

Download SKILL.mdSave it as .claude/skills/binlog-failure-analysis/SKILL.md (or your agent's skills folder).
name
binlog-failure-analysis
description
Analyze MSBuild binary logs to diagnose build failures. USE FOR: build errors that are unclear from console output, diagnosing cascading failures across multi-project builds, tracing MSBuild target execution order, and generally any MSBuild build issues. Requires an existing .binlog file. DO NOT USE FOR: generating binlogs (use binlog-generation), non-MSBuild build systems.
license
MIT

Analyzing MSBuild Failures with Binary Logs

This skill diagnoses MSBuild build failures from a .binlog file. The preferred path uses the binlog MCP server (Microsoft.AITools.BinlogMcp, exposed under the binlog MCP namespace) which is bundled with this plugin. If the MCP server is not available, fall back to the binlog replay workflow at the bottom.

Primary workflow — binlog MCP

The MCP server exposes structured tools for inspecting a .binlog without parsing text logs. Call them directly instead of replaying the binlog to a text file. Call tools/list for the MCP first if you are unsure which tools are available.

Important constraints:

  • The .binlog file is a binary format — do NOT try to cat, head, strings, or read it directly. Use only the MCP tools to query it.
  • The original source/project files might or might NOT be available on disk. Project files (.csproj, .props, .targets, App.config, etc.) - if you cannot locate them on disk, they can only be read from within the binlog via MCP tools (e.g., embedded/source file retrieval).
  • Synthesize findings as you go. Do not spend all available time investigating — once you have enough evidence, present your conclusions. A partial answer with clear reasoning is better than timing out mid-investigation.

Use the available MCP server tools to query the binary log for:

  • Build errors and warnings
  • MSBuild properties and their values
  • MSBuild items (PackageReference, ProjectReference, etc.)
  • Project evaluation data
  • Target execution details
  • File contents embedded in the binlog

Fallback workflow — text-log replay (when MCP is unavailable)

Use this only when the MCP server cannot be started (for example, on an older SDK or in an offline environment without access to the dotnet-tools NuGet feed).

Replay the binlog to text logs
bash
dotnet msbuild build.binlog -noconlog \
  -fl  -flp:v=diag;logfile=full.log;performancesummary \
  -fl1 -flp1:errorsonly;logfile=errors.log \
  -fl2 -flp2:warningsonly;logfile=warnings.log

PowerShell note: Use -flp:"v=diag;logfile=full.log;performancesummary" (quoted semicolons).

Search the text logs
bash
cat errors.log
grep -n -B2 -A2 "CS0246" full.log
grep -i "CoreCompile.*FAILED\|Build FAILED\|error MSB" full.log
grep 'Target "CoreCompile"' full.log | grep -oP 'project "[^"]*"'

Generating a binlog (only if none exists)

bash
dotnet build /bl:build.binlog

© microsoft, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/binlog-failure-analysis of microsoft/testfx.

Open the folder on GitHubat commit 44b9dcc

Used in 3 other repositories

We found 4 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 3 other GitHub owners. This page covers the copy in microsoft/testfx, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Binlog Failure Analysis next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Binlog Failure Analysis compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
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Fix Sentry Issuesbrianlovin/agent-config3751 repos~1.2kAutomated safety check: PassNone
Flowstudio Power Automate Debuggithub/awesome-copilot40k2 repos~5kAutomated safety check: PassMIT
Monte Carlo Remediationsickn33/agentic-awesome-skills47k1 repos~4kAutomated safety check: PassApache-2.0

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All 44 skills in this repo

  • Directory Build Organization

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  • Msbuild Antipatterns

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  • Resolve Project References

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    Guide for interpreting ResolveProjectReferences time in MSBuild performance summaries.

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Works with

Categories

Questions about Binlog Failure Analysis

What does Binlog Failure Analysis do?

Analyze MSBuild binary logs to diagnose build failures. An agent skill from microsoft/testfx. Binlog Failure Analysis is an agent skill from microsoft/testfx, published by the product's own GitHub organization. Analyze MSBuild binary logs to diagnose build failures.

When should I use Binlog Failure Analysis?

Binlog Failure Analysis fits situations like: : build errors that are unclear from console output; diagnosing cascading failures across multi-project builds; tracing MSBuild target execution order; generally any MSBuild build issues.

How do I install Binlog Failure Analysis in Claude Code?

Run `npx skills add microsoft/testfx --skill binlog-failure-analysis -a claude-code`. Or copy the skill folder (.agents/skills/binlog-failure-analysis in microsoft/testfx) into .claude/skills/binlog-failure-analysis in your project. Claude Code loads it when a task matches its description.

How do I install Binlog Failure Analysis in Codex?

Run `npx skills add microsoft/testfx --skill binlog-failure-analysis -a codex`. Or copy the skill folder (.agents/skills/binlog-failure-analysis in microsoft/testfx) into .agents/skills/binlog-failure-analysis in your project. Codex loads it when a task matches its description.

Can I use Binlog Failure Analysis in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add microsoft/testfx --skill binlog-failure-analysis -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/binlog-failure-analysis, .gemini/skills/binlog-failure-analysis, .github/skills/binlog-failure-analysis and .opencode/skills/binlog-failure-analysis in your project.

What does Binlog Failure Analysis need to run?

Going by SKILL.md and its folder, Binlog Failure Analysis needs the command-line tools its instructions call (dotnet).

Does Binlog Failure Analysis access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Binlog Failure Analysis safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Binlog Failure Analysis use?

Binlog Failure Analysis is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Binlog Failure Analysis use?

About 730 tokens (SKILL.md is roughly 2.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Binlog Failure Analysis?

Skills that share tags, products or a category with Binlog Failure Analysis: Octocode Code Research (bgauryy/octocode, 946 stars), Triage (arcee-ai/nac, 279 stars), Fix Sentry Issues (brianlovin/agent-config, 375 stars) and Flowstudio Power Automate Debug (github/awesome-copilot, 40k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Binlog Failure Analysis?

microsoft (a GitHub organization, an official publisher) maintains it in microsoft/testfx, which has 1,047 GitHub stars. The repository holds 44 skills in this directory. The repository was last updated on October 7, 2026.

Source: microsoft/testfx on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.