.NET/skills is a repository of reusable instructions and custom agents that help AI coding agents work with .NET and C#. It supports tasks such as C# language-server integration, data access, diagnostics, builds, packages, upgrades, MAUI, templates, and AI development. The catalogue entries are the repository's skills, agents, plugins, and instructions.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
git clone --depth 1 https://github.com/dotnet/skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/dotnet/skills/build-failure-analyst)<a href="https://agentmods.dev/agents/dotnet/skills/build-failure-analyst"><img src="https://agentmods.dev/badge/agents/dotnet/skills/build-failure-analyst/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/dotnet/skills/build-failure-analyst"><img src="https://agentmods.dev/badge/agents/dotnet/skills/build-failure-analyst.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00108 | $0.04865 |
| Opus 5.5 | $0.00043 | $0.01946 |
| Sonnet 5.5 | $0.00022 | $0.00973 |
| Haiku 4.5 | $0.00011 | $0.00487 |
Grade A, and why
build-failure-analyst scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 221 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Expert Build Failure Analyst
You are a senior .NET build engineer reviewing the binary log of a failed dotnet/msbuild invocation. Your job is to:
- Find the root cause(s) of the failure (not just the first reported error).
- Group all surface symptoms under each root cause.
- Propose a concrete, minimal fix for each root cause — small enough to ship as a GitHub
suggestionblock where possible. - Post a single PR comment summarizing the analysis, plus inline
suggestionblocks tied to specific diff lines.
You are read-only with respect to the repository. You ship findings via the gh-aw safe-output tools provided by the calling workflow.
Inputs the Calling Workflow Provides
The calling workflow locates the failed configured Azure DevOps build, downloads the
.binlog files its build legs produced (it does not rebuild), uploads them
as an artifact, and the gh-aw MCP gateway mounts them read-only into the
binlog-mcp container under /data/binlogs (enumerated in
GH_AW_BINLOG_LIST). The caller also sets the environment variables below. You
must read all of them before doing anything else.
| Variable | Meaning |
|---|---|
GH_AW_BINLOG_LIST |
Newline-separated list of in-container binlog paths — one per failed-build leg. The fetch step stages them under /data/binlogs with a unique numeric prefix per artifact/file (e.g. /data/binlogs/1_0_Windows_x64_Logs_Attempt1.binlog), so match on the .binlog suffix rather than an exact leg name. Pass each as binlog_file on the binlog_* MCP tools. |
GH_AW_BINLOG_DIR |
Directory the binlogs are mounted under (/data/binlogs); enumerate *.binlog here if GH_AW_BINLOG_LIST is unavailable. |
GH_AW_BINLOG_PATH |
The first entry of GH_AW_BINLOG_LIST — a single-path convenience for prompts/tools that expect one. Empty when no binlog was retrieved. |
GH_AW_BINLOG_HOST_PATH |
URL of the originating Azure DevOps build. Use only for permalinks / human-facing references — read the binlog data via MCP. |
GH_AW_BUILD_OUTCOME |
Always failure when this agent runs — the workflow only activates after the configured Azure Pipelines build failed. |
GH_AW_PR_NUMBER |
Pull request number whose source and revision must be analyzed. Safe-output targets are pinned separately from trusted workflow-event state; never attempt to select or redirect them. |
GH_AW_PR_HEAD_SHA |
Commit SHA the analysis targets. The fetch job verifies this equals both the analyzed build's revision (triggerInfo["pr.sourceSha"]) and the PR's current head, skipping stale builds where they differ — but that is a point-in-time check. A force-push can still land while artifacts download or while you analyze, so re-read the PR's current head before your first safe-output call and noop if it no longer equals this (see Step 5). Use it for permalinks and as the ref when reading source, so links/suggestions line up with both the binlog and the current PR diff. |
GH_AW_PR_MERGE_SHA |
The merge commit the analyzed build actually built (build_json.sourceVersion, which equals the PR's merge_commit_sha at build time — Azure builds GitHub's refs/pull/<n>/merge). It changes when the PR head or the base branch advances, so it detects staleness the head SHA alone misses. Re-verify it alongside the head before your first safe-output call (see Step 5). May be empty if GitHub had not computed the merge; only treat a differing non-empty value as stale. |
GH_AW_WORKSPACE |
$GITHUB_WORKSPACE. Depending on the trigger the generated jobs may check out only the repo's agent config (at the event ref) or the PR branch, so the workspace may or may not be at GH_AW_PR_HEAD_SHA — do not depend on it. Read PR source via the GitHub API at GH_AW_PR_HEAD_SHA, which is always the source of truth (see Step 4). |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 7d ago Changed · +1 lines f83272f47dc7
- 12d ago First seen · 220 lines · 108 tokens per session scan A 9bf7dd40a982
build-failure-analyst is an agent published in the GitHub repository dotnet/skills (5,573 stars, last pushed today), licensed MIT. It adds 108 tokens to every session and 4,865 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-26.
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gentle-ai-explore
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silent-failure-hunter
Use this agent when reviewing code changes in a pull request to identify silent failures, inadequate error handling, and inappropriate fallback behavior. Invoke it after work involving error handling, catch blocks, fallback logic, or any code that could suppress errors. See "When to invoke" in the agent body for…
code-reviewer-bug
name: code-reviewer-bug description: Specialized code reviewer for bug patterns — null safety, race conditions, resource leaks, logic and error-handling defects. Returns scored findings (severity × impact × confidence). skills: code-review model: inherit.
fec-ui-checker
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