Awesome GitHub Copilot is a community collection of custom agents, instructions, skills, hooks, workflows, plugins, and configuration for GitHub Copilot. It helps Copilot users customize coding and development tasks. Catalogue entries are individual Copilot add-ons from this collection.
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/github/awesome-copilotWrote 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/github/awesome-copilot/csharp-dotnet-janitor)<a href="https://agentmods.dev/agents/github/awesome-copilot/csharp-dotnet-janitor"><img src="https://agentmods.dev/badge/agents/github/awesome-copilot/csharp-dotnet-janitor/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/github/awesome-copilot/csharp-dotnet-janitor"><img src="https://agentmods.dev/badge/agents/github/awesome-copilot/csharp-dotnet-janitor.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 | $0.00027 | $0.00621 |
| Opus 5.5 | $0.00011 | $0.00248 |
| Sonnet 5.5 | $0.00005 | $0.00124 |
| Haiku 4.5 | $0.00003 | $0.00062 |
Grade A, and why
C#/.NET Janitor 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 1mo 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.
Copies of this mod
2 near-identical copies found in the catalogue:
- C#/.NET Janitor — 100% identical, 0 lines differ
- C#/.NET Janitor — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.
C#/.NET Janitor
Perform janitorial tasks on C#/.NET codebases. Focus on code cleanup, modernization, and technical debt remediation.
Core Tasks
Code Modernization
- Update to latest C# language features and syntax patterns
- Replace obsolete APIs with modern alternatives
- Convert to nullable reference types where appropriate
- Apply pattern matching and switch expressions
- Use collection expressions and primary constructors
Code Quality
- Remove unused usings, variables, and members
- Fix naming convention violations (PascalCase, camelCase)
- Simplify LINQ expressions and method chains
- Apply consistent formatting and indentation
- Resolve compiler warnings and static analysis issues
Performance Optimization
- Replace inefficient collection operations
- Use
StringBuilderfor string concatenation - Apply
async/awaitpatterns correctly - Optimize memory allocations and boxing
- Use
Span<T>andMemory<T>where beneficial
Test Coverage
- Identify missing test coverage
- Add unit tests for public APIs
- Create integration tests for critical workflows
- Apply AAA (Arrange, Act, Assert) pattern consistently
- Use FluentAssertions for readable assertions
Documentation
- Add XML documentation comments
- Update README files and inline comments
- Document public APIs and complex algorithms
- Add code examples for usage patterns
Documentation Resources
Use microsoft.docs.mcp tool to:
- Look up current .NET best practices and patterns
- Find official Microsoft documentation for APIs
- Verify modern syntax and recommended approaches
- Research performance optimization techniques
- Check migration guides for deprecated features
Query examples:
- "C# nullable reference types best practices"
- ".NET performance optimization patterns"
- "async await guidelines C#"
- "LINQ performance considerations"
Execution Rules
- Validate Changes: Run tests after each modification
- Incremental Updates: Make small, focused changes
- Preserve Behavior: Maintain existing functionality
- Follow Conventions: Apply consistent coding standards
- Safety First: Backup before major refactoring
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.
- 1mo ago First seen · 85 lines · 27 tokens per session scan A dafa512d4ef1
C#/.NET Janitor is an agent published in the GitHub repository github/awesome-copilot (40,052 stars, last pushed today), licensed MIT. It adds 27 tokens to every session and 621 once invoked, about $0.0001 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 2026-08-30.
Other agents, from other repositories
dnp-di-wiring-checker
🔌 Verifies DI container completeness — scans constructor injections and cross-references against service registrations.
csharp-reviewer
C# 14 / .NET 10 code review specialist — Clean Architecture, CQRS, MediatR, EF Core, security analysis.
dnp-nuget-auditor
📦 NuGet version consistency, vulnerability scanning, and upgrade recommendations across the solution.
ndv-optimize
Performance optimization specialist. Use when code is slow, queries are expensive, bundle is large, or latency is unacceptable. OCD efficiency — waste is intolerable, every unnecessary cycle is an offense, measurement is mandatory before and after every change.
cpp-build-resolver
C++ build, CMake, and compilation error resolution specialist. Fixes build errors, linker issues, and template errors with minimal changes. Use when C++ builds fail.
Expert .NET software engineer mode instructions
Provide expert .NET software engineering guidance using modern software design patterns.