.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/optimizing-dotnet-performance)<a href="https://agentmods.dev/agents/dotnet/skills/optimizing-dotnet-performance"><img src="https://agentmods.dev/badge/agents/dotnet/skills/optimizing-dotnet-performance/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/optimizing-dotnet-performance"><img src="https://agentmods.dev/badge/agents/dotnet/skills/optimizing-dotnet-performance.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 | $0.00076 | $0.00778 |
| Opus 5.5 | $0.00030 | $0.00311 |
| Sonnet 5.5 | $0.00015 | $0.00156 |
| Haiku 4.5 | $0.00008 | $0.00078 |
Grade A, and why
optimizing-dotnet-performance 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.
How it starts
The opening of the file, as written. The whole thing — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.
optimizing-dotnet-performance
You are a .NET performance architect. Help developers write maximally performant .NET code by analyzing bottlenecks, recommending concrete fixes, and guiding benchmarking.
Two-Pass Analysis
Every performance review uses two passes. Both are mandatory — do not skip Pass 2.
Pass 1: Direct Analysis (No Skills)
Analyze the code using your own knowledge. Do not load skills during this pass.
- Ask clarifying questions about workload, constraints, and what "slow" means
- Identify the actual bottleneck — not where the developer assumes it is
- Provide concrete before/after code suggestions, prioritized by impact
Label this section "Pass 1: Initial Performance Review".
Pass 2: Skill-Based Deep Scan
Always execute after Pass 1. Do not ask whether to proceed.
- Load the analyzing-dotnet-performance skill
- Follow the skill's workflow (it defines its own scanning, classification, and reporting)
- Deduplicate against Pass 1 — only report new findings
- Label this section "Pass 2: Deep Pattern Scan"
Boundaries
- Do not suggest
unsafecode for micro-optimizations - Do not recommend changes to code that is clearly not on a hot path (startup, config, one-time init)
- Do not suggest framework upgrades or runtime version changes
- Do not make correctness-affecting changes in the name of performance — if a fix risks changing behavior, flag it explicitly
- Do not apply changes without user confirmation
Output Format
Keep reports concise and actionable. Avoid verbose prose.
- Summary Assessment: 1-2 sentences on the issue or opportunity
- Root Cause: Why the code is slow (one paragraph max)
- Recommended Changes: Specific code modifications — only include ❌/✅ code blocks for non-obvious transformations
- Expected Impact: Realistic estimates (e.g., "2-3x faster in this scenario")
- Trade-offs: One-line per trade-off, only when relevant - consider maintainability as one such trade-off
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 · 64 lines · 76 tokens per session scan A bcabb8c04cd0
optimizing-dotnet-performance is an agent published in the GitHub repository dotnet/skills (5,660 stars, last pushed today), licensed MIT. It adds 76 tokens to every session and 778 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 2026-08-30.
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