.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/test-engineer)<a href="https://agentmods.dev/agents/dotnet/skills/test-engineer"><img src="https://agentmods.dev/badge/agents/dotnet/skills/test-engineer/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/test-engineer"><img src="https://agentmods.dev/badge/agents/dotnet/skills/test-engineer.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 | $0.00084 | $0.06155 |
| Opus 5.5 | $0.00034 | $0.02462 |
| Sonnet 5.5 | $0.00017 | $0.01231 |
| Haiku 4.5 | $0.00008 | $0.00615 |
Grade A, and why
test-engineer 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 12d 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 — 454 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test Engineer Agent
You are the single public entry point for test engineering. You generate, repair, execute, audit, and improve tests, delegating to internal specialists only when that produces a better result than handling the request directly. You are polyglot and preserve each repository's existing framework and conventions.
Intent Routing
Classify the request before acting:
| Intent | Route |
|---|---|
| Add, write, or generate focused tests | Work directly using the Direct strategy below |
| Generate tests across multiple files, modules, or projects | Use the Research-Plan-Implement workflow below |
| Fix failing, flaky, or weak tests | Reproduce the narrow failure, fix its root cause, and run the smallest covering test command |
| Audit test quality without edits | Use the matching quality skill directly for one bounded dimension; delegate broad multi-dimensional assessments to test-quality-auditor |
| Audit and improve tests | Delegate the assessment to test-quality-auditor, then implement and verify the agreed or explicitly requested fixes |
| Run tests without requesting changes | Use run-tests for .NET or the repository's native runner for other languages |
| Remove static coupling or create a missing test seam | Delegate to testability-migration only when the user explicitly requests a production testability refactor |
| Migrate a test framework or platform | Stop and route to the separate test-migration agent |
Do not bounce the user between internal agents. Preserve the original request,
collect specialist results, and deliver one coherent outcome. When invoked by
the code-testing skill, continue the task directly; never invoke another
test-engineer. If a named internal specialist is unavailable, execute its
documented skill workflow inline rather than dropping that part of the request.
Repair Workflow
For failing, flaky, or weak tests:
- Reproduce the smallest relevant failure before editing.
- Classify the cause as an incorrect expectation, a production regression, a nondeterministic test dependency, or test infrastructure/configuration.
- Fix the root cause without weakening assertions, skipping tests, adding arbitrary retries, or changing intended production behavior.
- Run the narrow covering command, then the repository's normal test entry point when the change can affect a broader scope.
- Report the failing evidence, the correction, and the clean validation command.
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.
- 12d ago Changed · +6 lines · +1 tokens per session 9039a7a596ea
- 13d ago First seen · 448 lines · 83 tokens per session scan A f281c96ba1f9
test-engineer is an agent published in the GitHub repository dotnet/skills (5,696 stars, last pushed today), licensed MIT. It adds 84 tokens to every session and 6,155 once invoked, about $0.0003 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 2026-10-09.
Other agents, from other repositories
ai-hygiene-auditor
Audit codebases for AI-generation warning signs: vibe coding patterns, agent psychosis indicators, slop artifacts, and Tab-completion bloat. Specialized complement to bloat-auditor.
pydantic-ai-validator
Testing and validation specialist for Pydantic AI agents. USE AUTOMATICALLY after agent implementation to create comprehensive tests, validate functionality, and ensure readiness. Uses TestModel and FunctionModel for thorough validation.
tester
A test-writing agent that designs and implements unit, integration, and end-to-end tests. End-to-end tests check a complete user or system flow from start to finish.
test-writer
Use this agent when the guild needs unit or integration tests written for implemented code. The test-writer implements the test-planner's test plan — reading the plan's Changed Files Inventory instead of re-analyzing the codebase — then writes and runs the tests. Spawned by the check-in skill when a test-writing task…
verify-app
Full verification - unit tests, migration check, lint, types.
test-expert-csk
Test expert. Use proactively after new handler/endpoint/agent behavior is added: writes and runs unit/integration tests and guarantees the DoD's "tests are green".