dotnet-diag
By dotnet
Diagnose .NET performance issues and crashes by scanning C# code for 50+ anti-patterns with fixes, collecting traces and dumps from production environments including Docker and Kubernetes on Windows/Linux, symbolicating Android tombstones, analyzing CLR activation logs, and running BenchmarkDotNet microbenchmarks for optimizations.
Component Overview
Install
npx claudepluginhub dotnet/skills --plugin dotnet-diagComponent Details
Skills (6)
Scans .NET code for ~50 performance anti-patterns across async, memory, strings, collections, LINQ, regex, serialization, and I/O with tiered severity classification. Use when analyzing .NET code for optimization opportunities, reviewing hot paths, or auditing allocation-heavy patterns.
Symbolicate the .NET runtime frames in an Android tombstone file. Extracts BuildIds and PC offsets from the native backtrace, downloads debug symbols from the Microsoft symbol server, and runs llvm-symbolizer to produce function names with source file and line numbers. USE FOR triaging a .NET MAUI or Mono Android app crash from a tombstone, resolving native backtrace frames in libmonosgen-2.0.so or libcoreclr.so to .NET runtime source code, or investigating SIGABRT, SIGSEGV, or other native signals originating from the .NET runtime on Android. DO NOT USE FOR pure Java/Kotlin crashes, managed .NET exceptions that are already captured in logcat, or iOS crash logs. INVOKES Symbolicate-Tombstone.ps1 script, llvm-symbolizer, Microsoft symbol server.
Diagnoses .NET Framework CLR activation issues using CLR activation logs (CLRLoad logs) produced by mscoree.dll. Use when: the shim picks the wrong runtime, fails to load any runtime, shows unexpected .NET 3.5 Feature-on-Demand (FOD) dialogs, unexpectedly does NOT show FOD dialogs, loads both v2 and v4 into the same process causing failures, or any time someone is wondering "what is happening with .NET Framework activation?"
Guide developers through capturing diagnostic artifacts to diagnose production .NET performance issues. Use when the user needs help choosing diagnostic tools, collecting performance data, or understanding tool trade-offs across different environments (Windows/Linux, .NET Framework/modern .NET, container/non-container).
Configure and collect crash dumps for modern .NET applications. USE FOR: enabling automatic crash dumps for CoreCLR or NativeAOT, capturing dumps from running .NET processes, setting up dump collection in Docker or Kubernetes, using dotnet-dump collect or createdump. DO NOT USE FOR: analyzing or debugging dumps, post-mortem investigation with lldb/windbg/dotnet-dump analyze, profiling or tracing, or for .NET Framework processes.
Activate this skill when BenchmarkDotNet (BDN) is involved in the task — creating, running, configuring, or reviewing BDN benchmarks. Also activate when microbenchmarking .NET code would be useful and BenchmarkDotNet is the likely tool. Consider activating when answering a .NET performance question requires measurement and BenchmarkDotNet may be needed. Covers microbenchmark design, BDN configuration and project setup, how to run BDN microbenchmarks efficiently and effectively, and using BDN for side-by-side performance comparisons. Do NOT use for profiling/tracing .NET code (dotnet-trace, PerfView), production telemetry, or load/stress testing (Crank, k6).
README
.NET Agent Skills
This repository contains the .NET team's curated set of core skills and custom agents for coding agents. For information about the Agent Skills standard, see agentskills.io.
What's Included
| Plugin | Description |
|---|---|
| dotnet | Collection of core .NET skills for handling common .NET coding tasks. |
| dotnet-data | Skills for .NET data access and Entity Framework related tasks. |
| dotnet-diag | Skills for .NET performance investigations, debugging, and incident analysis. |
| dotnet-msbuild | Comprehensive MSBuild and .NET build skills: failure diagnosis, performance optimization, code quality, and modernization. |
| dotnet-nuget | NuGet and .NET package management: dependency management and modernization. |
| dotnet-upgrade | Skills for migrating and upgrading .NET projects across framework versions, language features, and compatibility targets. |
| dotnet-maui | Skills for .NET MAUI development: environment setup, diagnostics, and troubleshooting. |
| dotnet-ai | AI and ML skills for .NET: technology selection, LLM integration, agentic workflows, RAG pipelines, MCP, and classic ML with ML.NET. |
| dotnet-template-engine | .NET Template Engine skills: template discovery, project scaffolding, and template authoring. |
| dotnet-test | Skills for running, diagnosing, and migrating .NET tests: test execution, filtering, platform detection, and MSTest workflows. |
| dotnet-aspnet | ASP.NET Core web development skills including middleware, endpoints, real-time communication, and API patterns. |
Installation
🚀 Plugins - Copilot CLI / Claude Code
- Launch Copilot CLI or Claude Code
- Add the marketplace:
/plugin marketplace add dotnet/skills - Install a plugin:
/plugin install <plugin>@dotnet-agent-skills - Restart to load the new plugins
- View available skills:
/skills - View available agents:
/agents - Update plugin (on demand):
/plugin update <plugin>@dotnet-agent-skills
VS Code / VS Code Insiders (Preview)
[!IMPORTANT]
VS Code plugin support is a preview feature and subject to change. You may need to enable it first.
// settings.json
{
"chat.plugins.enabled": true,
"chat.plugins.marketplaces": ["dotnet/skills"]
}
Once configured, type /plugins in Copilot Chat or use the @agentPlugins filter in Extensions to browse and install plugins from the marketplace.
Codex CLI
Skills in this repository follow the agentskills.io open standard and are compatible with OpenAI Codex.
Install individual skills using the skill-installer CLI with the GitHub URL:
$ skill-installer install https://github.com/dotnet/skills/tree/main/plugins/<plugin>/skills/<skill-name>
⚡ Agentic Workflows
Some plugins include GitHub Agentic Workflow templates for CI/CD automation:
- Install the
gh awCLI extension - Copy the desired workflow
.mdfiles and theshared/directory to your repository's.github/workflows/ - Compile and commit:
gh aw compile - Commit both the
.mdand generated.lock.ymlfiles
Contributing
See CONTRIBUTING.md for contribution guidelines and how to add a new plugin.
License
See LICENSE for details.
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