FSharp.Refactor

Name: FSharp.Refactor
Author: Thorium

by Thoriumversion 0.8.45i★ –iRuns on your computer

Registry nameio.github.Thorium/fsharp-refactor

Install

Overview

Description from the maker (original English)

Offline analyzers that find and fix intent-hiding, slow or noisy F#, including agent-written code.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
The registry lists no key to fill in.

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "fsharp-refactor": {
      "command": "dnx",
      "args": [
        "fsharp-refactor",
        "--yes",
        "--mcp"
      ]
    }
  }
}

Run this in your terminal

claude mcp add fsharp-refactor -- dnx fsharp-refactor --yes --mcp

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "fsharp-refactor": {
      "command": "dnx",
      "args": [
        "fsharp-refactor",
        "--yes",
        "--mcp"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "fsharp-refactor": {
      "type": "stdio",
      "command": "dnx",
      "args": [
        "fsharp-refactor",
        "--yes",
        "--mcp"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 6, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account Thorium, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

More stars than 0% of the other 32435 servers in this category
Published to the registry more recently than 62% of the other 32435 servers in this category
Basic checks equal to or better than 100% of the other 32435 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is FSharp.Refactor safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.8.45) reached the registry 23 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need .NET on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, Apify MCP Server

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README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

FSharp.Refactor

Let's remove parentheses from the internet

Functional refactoring suggestions for F#. The tool clarifies the (agent-generated or old) code's intent, reduces non-alphanumeric noise, and uses built-in .NET libraries more efficiently.

light bulb quick fixes in your editor
command-line tool that applies them in bulk.

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

This project is the big brother of CSharp.Refactor

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 fsharp-refactor

fsharp-refactor Your.fsproj --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:

fsharp-refactor Your.fsproj --api-changes

It refuses a compilation that does not already build, and fails loudly if applying ever introduces an error.

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

fsharp-refactor Your.fsproj

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:


`Your.fsproj`	one project
`Thing.fs`	one source file - its project is found and analysed, but only that file is edited
`build.fsx`	one script - no MSBuild step at all, so it starts instantly. A script with unresolvable references is not refused: the syntactic rules still run over it (an fsi-run script may reference things only the run supplies)
`Your.sln`, `Your.slnx`	every F# project the solution lists
`src/`	the solution in that directory, or the projects beneath it
`"src/*/.fsproj"`	everything the glob matches

What it changes

Examples:

	Before	After
Correctness	`let s = new FileStream(p, m)`	`use s = new FileStream(p, m)`
Correctness	`raise (Exception "boom")`	`failwith "boom"`
Performance	`s.Contains "x"`	`s.Contains 'x'`
Performance	`xs \	> Seq.toList \	> List.map f`	`xs \	> Seq.map f \	> Seq.toList`
Idiom	`match b with \	true -> 1 \	false -> 0`	`if b then 1 else 0`
Redundancy	`new StringBuilder()`	`StringBuilder()`
Redundancy	`[ ]`	`[ ]`
Diagnostics	`failwith "Error"`	`failwith $"Error, calling f with x: {x}"`

A spread of what the 150-odd rules do - the full list is in Refactorings:

Editor and CI setup

The analyzers ship as FSharp.Refactor.Analyzers. The package is a development dependency: it only produces hints and quick fixes - nothing from it flows into your compiled output.

NOTE: EVEN WHEN ADDING A NUGET REFERENCE, THIS ANALYSER WILL NOT COME TO OUTPUT PATH (BIN) AND WILL NOT BE PART OF YOUR PROJECT.

VS Code / Ionide

Easiest: install the FSharp.Refactor VS Code extension

it bundles the analyzers and (with your consent) wires them into

Ionide's settings globally, so every F# project gets the hints with no per-project setup.

Or wire a single project by hand: reference the package from the project you want analyzed:

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

then point Ionide at the restored analyzers in .vscode/settings.json:

"FSharp.enableAnalyzers": true, "FSharp.analyzersPath": [ "~/.nuget/packages/fsharp.refactor.analyzers/ /analyzers/dotnet/fs" ] }

replacing with the version restore actually picked (the NuGet cache always keys folders by version, so this one path cannot float; check with ls ~/.nuget/packages/fsharp.refactor.analyzers/). On Windows the cache lives under %USERPROFILE%\.nuget\packages. Suggestions appear as Hint-severity diagnostics with a light-bulb one-click fix.

FsAutoComplete 0.85+ titles each fix by what it writes (Fix FR0136 → Guid.NewGuid()); an older one says only Fix FR0136. Ionide bundles its own FsAutoComplete; to run a newer one, dotnet tool install -g fsautocomplete and set FSharp.fsac.netCoreDllPath to its fsautocomplete.dll (the extension above offers to do both).

The package ships the analyzers built against TWO FSharp.Analyzers.SDK versions side by side - FSharp.Refactor.Analyzers.Ionide.dll for SDK 0.35.0 (what stock Ionide's FsAutoComplete bundles, 7.31.x and earlier) and FSharp.Refactor.Analyzers.dll for SDK 0.37.2 (the CLI, and FsAutoComplete 0.84+). The SDK loads only the assembly matching its own version and logs a skip line for the other, so every host picks the one it can use and no configuration choice is needed.

If no suggestions appear, open Output -> "F# Language Service": it names the analyzer dlls it scanned and how many analyzers loaded, and a version-pairing skip is spelt out there rather than surfacing in the editor.

Visual Studio 2022-2026

Install the FSharp.Refactor Visual Studio extension (user-facing overview): squiggles and Ctrl+. quick fixes in full Visual Studio, analyzed through an FsAutoComplete sidecar. One prerequisite: dotnet tool install -g fsautocomplete.

CLI / CI

dotnet tool install --global fsharp-analyzers

fsharp-analyzers --project src/YourProject.fsproj --analyzers-path ~/.nuget/packages/fsharp.refactor.analyzers/ /analyzers/dotnet/fs --code-root . --report analysis.sarif

fsharp-analyzers is the analyzer HOST, and it is the dotnet tool you install. This package is not a tool: it is a library of analyzer assemblies the host loads, so it is passed as a directory rather than installed. That directory sits in the NuGet cache because an analyzer package deliberately has no lib/ folder and is marked a development dependency - a PackageReference therefore puts nothing in your bin, and after a restore, the cache is where the assemblies live. --analyzers-path takes any folder holding them and searches it recursively.

The CLI only REPORTS; it never edits your files, which is what you want in CI (SARIF output works in GitHub code scanning). To apply the fixes, use our own tool below. Individual rules can be turned off per repository with a fsharprefactor.json - see Configuration below.

Applying fixes from the command line

The fsharp-refactor dotnet tool applies the quick fixes directly to your files:

dotnet tool install --global fsharp-refactor

fsharp-refactor Your.fsproj [--dry-run] [--codes FR0002,FR0031] [--api-changes] [--jobs 4] [--max-passes 5]

(or from this repository: dotnet run --project src/FSharp.Refactor.Tool -c Release -- Your.fsproj ...)

For a project it takes the exact compiler arguments from MSBuild; for a script FCS resolves the references itself and MSBuild never runs. Either way it then runs every analyzer, applies non-overlapping fixes bottom-up, and re-analyzes until a pass applies nothing - a fix can enable further fixes. It refuses a compilation that already has errors, and fails loudly if applying ever introduces one.

Warnings as errors: the project's own settings decide, and the tool never overrides them - its verification is the build your CI runs. The in-memory typecheck takes the compiler's own arguments, so --warnaserror and turn an F# warning a fix raises into an error the pass rolls back. A C# project that references the F# one and turns an analyzer warning into an error (error CA1859, error IDE0005) fails the verification build as code, not as tooling noise, and the run says which setting to change if you want such fixes anyway ( CA1859 , or dotnet_diagnostic.CA1859.severity = suggestion). works too, but silences the analyzer for everyone.

Flag
`--dry-run`	Report only: lists every fix it would make, with file and position, and writes nothing. Rewriting is never implicit - drop the flag to let it edit.
`--codes FR0002,FR0031`	Restrict the run to chosen rules; the other analyzers do not run.
`--categories`	Restrict the run to kinds of rule: `correctness`, `performance`, `idiom`, `cosmetic`. Combined with `--codes` it narrows further, in either order. The analyzers of the rules left out do not run at all. A filtered run can stop at a point a full run passes through: FR0157 (idiom) leaves a `	_ ->` that FR0072 (correctness) closes in the next pass of a full run, so an idiom-only run leaves it open. See Someone else's codebase.
`--jobs`	Typecheck that many files at once (default 4, clamped to 2-4 by core count). Trades CPU for wall clock; because FCS reuses each file's prefix within one incremental build, the gain peaks around 4 and reverses if pushed higher. `--jobs 1` is the sequential sweep.
`--framework`	Analyse against this target framework instead of the narrowest one - see below.
`--max-passes`	Fix-then-reanalyze iterations (default 5). A pass after the first sweeps only the files the previous pass changed and those compiled after the first of them.
`--help`	The same list, from the tool itself (`-h` and `/?` also work).
`--api-changes`	Also apply the cross-file fixes described below.
`--no-if-defs`	Never emit `#if`/`#else`/`#endif` pairs for capability fixes on multi-targeted projects (see below). The fixes stay plain, and any the legacy frameworks reject are put back by the final build check.
`--report`	Write every finding the run surfaced to a file; the extension picks the format. `.sarif` (or `.json`) is SARIF 2.1.0 - what GitHub code scanning renders as inline PR annotations; `.html` is a self-contained page with per-rule grouping, highlighted source, before/after fixes and category filters; `.csv` is one row per finding for a spreadsheet. Pairs naturally with `--dry-run` for a CI lint gate. See CI setup below. A many-target run rewrites the report after every target, so a crash or a Ctrl-C an hour in still leaves what was found. Pointing the tool at a workspace of checkouts - a directory with no solution of its own whose sub-directories carry theirs, `C:git` say - analyses each checkout on its own (its solutions honoured, its `fsharprefactor.json` applied) into the one report, with paths relative to the workspace.
`--baseline`	The ratchet: findings whose fingerprints appear in this earlier `--report` output are neither reported nor fixed - only what is NEW surfaces. Fingerprints hash the rule code, file name and normalized surrounding source, so they survive line shifts, other edits in the file, and different checkouts. Triage once, ratchet forever.
`--fail-on-findings`	Exit 3 when any finding survives the filters - the hard CI gate. The full exit contract: 0 clean, 1 analysis or apply failure, 2 usage error, 3 findings (only with this flag).

| --notes [on|off|only] | --notes (or --notes on) lists fix-less advisory notes inline; --notes only is the review pass described next. By default a run prints its FIXES - the product - and ends with one per-category note count (41 advisory note(s) held: …); SARIF (--report) and --format json

Only the beginning is shown; read the rest in the repo

FSharp.Refactor

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

Apify MCP Server

README from the maker

FSharp.Refactor

Using it

Quick start

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.

What it changes

Editor and CI setup

VS Code / Ionide

Visual Studio 2022-2026

CLI / CI

Applying fixes from the command line