Best AI Agent Skills for .NET and C# Developers (2026)

Our directory holds 1,873 agent skills. Filter them for anything about .NET or C# and you are left with fewer than ten, and one of those is a Chinese-language link collection.

Compare that to Python, which has skills for testing, packaging, notebooks, type checking and half a dozen frameworks. The gap is not because .NET developers are rare. It is because the agent-skills scene grew out of the Python and TypeScript communities, and three years later the tooling still reflects where it started.

So this page is shorter on entries than our other language guides, and more useful for it. Here is what exists, what is stale, and what to do about the parts nobody has built.

What exists, honestly graded

Note the shape: one real SDK, one dead library, and several things that are documents rather than skills. Read the status column before the star column.

The one that matters

MCP C# SDK

modelcontextprotocol/csharp-sdk, official tier, audited, 4,487 stars, pushed 20 August 2026. The C# implementation of the Model Context Protocol, maintained in the protocol's own GitHub organisation.

It has shipped 47 NuGet releases and reached 2.2.0, which is worth stating plainly because the preview-era tutorials still floating around show APIs from the 0.x line that no longer match. If a guide's imports look unfamiliar, check its date before assuming you did something wrong.

The package split tells you which one to take:

dotnet add package ModelContextProtocol.Core        # client and low-level server, fewest dependencies
dotnet add package ModelContextProtocol             # hosting and DI extensions, the usual choice
dotnet add package ModelContextProtocol.AspNetCore  # HTTP-based servers

There are two more for MCP Apps and long-running tasks with status polling. Most projects want the middle one.

Our database lists this with an npx -y modelcontextprotocol/csharp-sdk install string. It is a NuGet library, not an npm package, and there is nothing to npx. Use the dotnet add package line above.

Deep dive: /skills/csharp-sdk

MCPSharp

afrise/MCPSharp, MIT, 374 stars, on NuGet at 1.0.11. A community library for building MCP servers in .NET, installed with dotnet add package MCPSharp.

The last push was 20 October 2025. Ten months of silence in a protocol that has changed materially in that time is disqualifying for new work. It appears here because it will show up in your searches and you should know why to skip it. The official SDK covers the same ground and is maintained.

Deep dive: /skills/mcpsharp

Documents that work as agent context

Two entries in our database are not installable at all, and both are more valuable than half the things that are.

CSharpGuidelines

dennisdoomen/CSharpGuidelines, 776 stars, updated 21 July 2026, covering C# up to version 14. A coding standard with design principles and rationale, maintained for well over a decade.

There is no install command; the useful move is to point your agent at it. Drop the relevant sections into your CLAUDE.md or AGENTS.md, or reference the repository from your project instructions. A model that has read an opinionated standard writes noticeably more consistent C# than one improvising house style per file. That is the closest thing to a "C# skill" available today, and you assemble it yourself.

Deep dive: /skills/csharpguidelines

MCP for Beginners

microsoft/mcp-for-beginners, MIT, official tier, 17,035 stars, pushed 21 August 2026. Microsoft's MCP curriculum, with samples across languages including C#.

Also not an MCP server, despite the install string our database generates for it. It is a course. For .NET developers it is the best-structured on-ramp available, and coming from Microsoft it tends to show the .NET path as a first-class citizen rather than an afterthought translated from the Python examples.

Deep dive: /skills/mcp-for-beginners

Analysis and review, where language-agnostic wins

C# is well served by static analysis, and the agent-facing entries here are not .NET-specific but do support it properly.

SonarQube MCP server

SonarSource/sonarqube-mcp-server, 630 stars, pushed 21 August 2026, maintained by SonarSource. C# is a first-class SonarQube language with a large rule set, and exposing that over MCP means the agent reads real analyser findings instead of forming opinions about your code from the text alone.

The server is a Java project, so it runs as a container or JAR rather than through npm. Vendor-maintained, which in this category counts for a lot.

Deep dive: /skills/sonarqube-mcp-server

Semgrep

semgrep/semgrep, LGPL-2.1, 16,342 stars, actively maintained. Pattern-based static analysis with C# support and rules you can write yourself, which is the part that matters for enforcing conventions no general linter knows about.

Deep dive: /skills/semgrep

One .NET-specific note on both: Roslyn analysers already run inside your build, and an agent that can read dotnet build warnings gets much of this for free. The reason to add an MCP layer is history and cross-file rules, not first-pass linting. If you have never turned on TreatWarningsAsErrors and a .editorconfig with the analyser severities you care about, do that before installing anything, because it costs nothing and the agent reads the output.

For workflow rather than analysis, the obra/superpowers collection, 275,614 stars and MIT, holds language-agnostic skills for test-driven development and for giving and receiving code review. Nothing in them assumes Python. One caveat on our own data: every sub-skill from that collection inherits the parent repository's star count, so a "275,571 stars" figure on an individual entry is the collection's total, not that skill's popularity.

Games, the one .NET niche with real tooling

Unity is written in C#, and Unity has an agent-tooling scene, so this corner is better served than the rest of .NET.

Unity MCP from IvanMurzak/Unity-MCP is Apache-2.0 with 3,956 stars and active development, giving an agent access to the editor. ET from egametang/ET is a 9,889-star Unity client and C# server framework, useful as a reference architecture for the server half of a game rather than as an agent tool.

Our comparison of Unity, Godot and Unreal MCP servers covers that ground properly, and agent skills for game developers sits alongside it.

What to do about the gap

The absence is an opportunity if you write .NET for a living. Three things are missing and none is hard.

A skill wrapping dotnet CLI conventions: project layout, dotnet test output parsing, dotnet format, central package management. A skill for Entity Framework migrations, which is exactly the kind of task where an agent needs a procedure rather than improvisation. And an ASP.NET Core skill covering minimal APIs, DI registration and the configuration model.

There is a fourth worth naming: NuGet dependency work. Package upgrades in a large solution mean reading release notes, checking target frameworks and resolving transitive conflicts, which is procedural enough to write down and tedious enough that nobody wants to. Our agent skills for dependency upgrades page covers the language-neutral version of that pattern.

Each is a markdown file with instructions. The skill authoring guide covers the mechanics. Publishing one now would make it the first of its kind, which is not a sentence you can write about a Python skill.

Related reading: agent skills for Java and Spring Boot, agent skills for Go, agent skills for code review, and the full list for developers.

FAQ

Is there an official .NET agent skill from Microsoft or Anthropic?

No. Microsoft's MCP curriculum includes C# samples and Anthropic's collection is language-neutral, but neither ships a .NET skill. The MCP C# SDK is a protocol library, not a skill.

Can I use Python or TypeScript skills on a C# codebase?

The workflow ones, yes. Test-driven development, code review and debugging skills describe a process and do not care about your language. Anything that shells out to a package manager or parses tool output will assume the wrong toolchain.

Should I build an MCP server in C# or switch languages for it?

Build it in C# if your codebase is C#. The official SDK reached 2.2.0 across 47 releases and has hosting and ASP.NET Core packages, so nothing about the .NET path is second-class any more. Switching languages for an MCP server means maintaining a second toolchain for a few hundred lines of code.

Why does your install command for these entries not work?

Because our ingestion pipeline assigns install strings by entry type and defaults to the npm-based MCP template. NuGet libraries, Java servers and course repositories all get caught by it. We are correcting these; the repository README is the authority, and the verified commands are on this page.

What is the fastest way to make an agent better at my C# codebase today?

Give it a written standard. Point it at CSharpGuidelines, add your own deviations, and put the result in CLAUDE.md. That single step changes output quality more than any tool on this page, and it takes an afternoon.