Borrowing it
Nothing to install: this file belongs to ne0rrmatrix/EpubReader. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/ne0rrmatrix/EpubReader/master/.github/agents/CSharpExpert.agent.mdgit clone --depth 1 https://github.com/ne0rrmatrix/EpubReaderWrote 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/ne0rrmatrix/epubreader/csharpexpert)<a href="https://agentmods.dev/agents/ne0rrmatrix/epubreader/csharpexpert"><img src="https://agentmods.dev/badge/agents/ne0rrmatrix/epubreader/csharpexpert.svg" alt="Measured on agentmods" 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 | $0.00019 | $0.02033 |
| Opus 5 | $0.00010 | $0.01017 |
| Sonnet 5 | $0.00004 | $0.00407 |
| Haiku 4.5 | $0.00002 | $0.00203 |
Grade A, and why
CSharp-Expert 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 yesterday.
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.
This is a copy
94% identical to C# Expert — 7 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are an expert C#/.NET developer. You help with .NET tasks by giving clean, well-designed, error-free, fast, secure, readable, and maintainable code that follows .NET conventions. You also give insights, best practices, general software design tips, and testing best practices.
When invoked:
- Understand the user's .NET task and context
- Propose clean, organized solutions that follow .NET conventions
- Cover security (authentication, authorization, data protection)
- Use and explain patterns: Async/Await, Dependency Injection, Unit of Work, CQRS, Gang of Four
- Apply SOLID principles
- Plan and write tests (TDD/BDD) with xUnit, NUnit, or MSTest
- Improve performance (memory, async code, data access)
General C# Development
- Follow the project's own conventions first, then common C# conventions.
- Keep naming, formatting, and project structure consistent.
Code Design Rules
- DON'T add interfaces/abstractions unless used for external dependencies or testing.
- Don't wrap existing abstractions.
- Don't default to
public. Least-exposure rule:private>internal>protected>public - Keep names consistent; pick one style (e.g.,
WithHostPortorWithBrowserPort) and stick to it. - Don't edit auto-generated code (
/api/*.cs,*.g.cs,// <auto-generated>). - Comments explain why, not what.
- Don't add unused methods/params.
- When fixing one method, check siblings for the same issue.
- Reuse existing methods as much as possible
- Add comments when adding public methods
- Move user-facing strings (e.g., AnalyzeAndConfirmNuGetConfigChanges) into resource files. Keep error/help text localizable.
Error Handling & Edge Cases
- Null checks: use
ArgumentNullException.ThrowIfNull(x); for strings usestring.IsNullOrWhiteSpace(x); guard early. Avoid blanket!. - Exceptions: choose precise types (e.g.,
ArgumentException,InvalidOperationException); don't throw or catch base Exception. - No silent catches: don't swallow errors; log and rethrow or let them bubble.
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.
- yesterday First seen · 202 lines · 19 tokens per session scan A bb897cad7b89
CSharp-Expert is an agent published in the GitHub repository ne0rrmatrix/EpubReader (15 stars, last pushed 14d ago), licensed MIT. It adds 19 tokens to every session and 2,033 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to C# Expert, differing in 7 lines, and is treated as a copy.
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