CSharp.Refactor MCP server

CSharp.Refactor

The C# little-sister of FSharp.Refactor

Functional refactoring suggestions for C#, implemented in F# on Roslyn. The rules care about correctness, measured performance and clear idiomatic C# — and deliberately not about naming, layout or conventions.

anything that hosts Roslyn analyzers)

• light bulb quick fixes in your editor (Visual Studio, VS Code, Rider,

• a command-line tool that applies them in bulk, build-verified

Suggestions are Info severity: they mark an opportunity, not a defect, and never gate your build.

Using it

The tool is fully offline: AI has been used to make it, but it doesn't use AI.

Quick start

Nothing to configure — the tool reads your project, reports what it would change, and only edits when you tell it to:

dotnet tool install --global csharp-refactor
csharp-refactor Your.csproj --dry-run --api-changes

That prints every fix it would make, with file and position, and writes nothing. When the list looks right, drop the flag to apply them:

csharp-refactor Your.csproj --api-changes

If you don't want change public methods / API, drop --api-changes:

csharp-refactor Your.fsproj

It refuses a compilation that does not already build, recompiles in memory after every pass, and builds the project for real at the end, putting the fixes back if that fails.

For light bulbs while you type, see VS Code / Ionide and Visual Studio IDE-plugin instructions below.

For agentic scenarios the dotnet tool supports MCP.

Using the tool:

Point it at whatever you have — the kind is read off the path:

Editor and CI setup

The analyzers ship as CSharp.Refactor.Analyzers, an ordinary Roslyn analyzer package. Reference it from the project you want analysed and every host — dotnet build, Visual Studio, VS Code's C# extension, Rider — loads it by itself:

<PackageReference Include="CSharp.Refactor.Analyzers" Version="*" PrivateAssets="all" />

The package is a development dependency: it only produces hints and quick fixes, and nothing from it reaches your compiled output or your bin.

Visual Studio 2022 / 2026

Install the CSharp.Refactor extension: every C# project opened in the IDE gets the suggestions and Ctrl+. fixes, with no project change and no effect on builds. Its Tools > CSharp.Refactor menu runs the csharp-refactor tool on the open solution (apply or dry run, with or without --api-changes), writes the SARIF report, opens the notes page and the .editorconfig block — the VS Code extension's commands, in Visual Studio. Or use the package reference above; both work, and a project with both sees each finding once.

VS Code

Install the CSharp.Refactor extension. It bundles the analyzers and, with your consent, wires them into every C# project on the machine through MSBuild's user ImportBefore hook (one props file under your profile, undone by a command). Or use the package reference.

CI

Shortened. The full README is on GitHub.