Roslyn MCP

Name: Roslyn MCP
Author: darylmcd

by darylmcdversion 5.0.0i★ –iRuns on your computer

Registry nameio.github.darylmcd/roslyn-mcp

Install

Overview

Description from the maker (original English)

Local-first MCP server for semantic C# analysis & refactoring via Roslyn & MSBuildWorkspace.

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).
You fill in yourself: ROSLYNMCP_SANCTIONED_ROOTS

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": {
    "roslyn": {
      "command": "dnx",
      "args": [
        "Darylmcd.RoslynMcp",
        "--yes"
      ],
      "env": {
        "ROSLYNMCP_SANCTIONED_ROOTS": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add roslyn --env ROSLYNMCP_SANCTIONED_ROOTS=your-value -- dnx Darylmcd.RoslynMcp --yes

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

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

{
  "mcpServers": {
    "roslyn": {
      "command": "dnx",
      "args": [
        "Darylmcd.RoslynMcp",
        "--yes"
      ],
      "env": {
        "ROSLYNMCP_SANCTIONED_ROOTS": "your-value"
      }
    }
  }
}

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": {
    "roslyn": {
      "type": "stdio",
      "command": "dnx",
      "args": [
        "Darylmcd.RoslynMcp",
        "--yes"
      ],
      "env": {
        "ROSLYNMCP_SANCTIONED_ROOTS": "your-value"
      }
    }
  }
}

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.

Values you fill in

ROSLYNMCP_SANCTIONED_ROOTS env
Server-owned filesystem boundary for path validation and solution discovery. Path-separator-delimited (';' on Windows, ':' on macOS/Linux). '.' scopes the server to its working directory. An empty va…

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 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account darylmcd, 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 18345 servers in this category
Published to the registry more recently than 80% of the other 18345 servers in this category
Basic checks equal to or better than 100% of the other 18345 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 Roslyn MCP 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 (5.0.0) reached the registry 9 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, ScienceShot science reference

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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.

Roslyn-Backed MCP Server

Local-first MCP (Model Context Protocol) server for semantic C# analysis, navigation, validation, and refactoring on real .sln / .slnx / .csproj workspaces. It uses Roslyn and MSBuildWorkspace, runs over stdio, and does not require Visual Studio. Refactoring tools follow a preview → apply discipline: previews return short-lived tokens, so agents can dry-run multi-file edits before mutating the workspace. It ships as a .NET global tool, a Claude Code plugin, and a source-buildable stdio host.

Correct package ID: Darylmcd.RoslynMcp · CLI: roslynmcp · Plugin: roslyn-mcp@roslyn-mcp-marketplace

Quick Start

Prerequisite: the .NET 10 SDK.

Option A — Install As A Global Tool

dotnet tool install -g Darylmcd.RoslynMcp

Update later with dotnet tool update -g Darylmcd.RoslynMcp.

Configure a filesystem boundary before first use. The global tool ships a binary, not a

config, and an unset boundary is fail-closed: every path-taking tool rejects its input.

Set ROSLYNMCP_SANCTIONED_ROOTS in your MCP client config (for example a project-scope .mcp.json):

`json

{

"mcpServers": {

"roslyn": {

"type": "stdio",

"command": "roslynmcp",

"env": { "ROSLYNMCP_SANCTIONED_ROOTS": "." }

}

`

. resolves against the server process's working directory, which your MCP client chooses; use an

absolute path to pin the boundary. See Setup.

Option B — Zero-Install Via `dnx` (.NET 10)

dnx resolves the package from NuGet on demand, without installing a global shim: run dnx Darylmcd.RoslynMcp. Pin a version for reproducible setups with Darylmcd.RoslynMcp@ . Configure the same ROSLYNMCP_SANCTIONED_ROOTS boundary as above; copy-paste configs live in docs/mcp-json-examples/, and details are in Setup.

Option C — Claude Code Plugin

/plugin marketplace add darylmcd/Roslyn-Backed-MCP

/plugin install roslyn-mcp@roslyn-mcp-marketplace

The plugin bundles 32 skills and safety hooks, then launches the exact release-matched Darylmcd.RoslynMcp package through dnx; it does not require a global roslynmcp shim. The first launch requires NuGet access unless the package is already cached. The plugin's bundled "." boundary resolves to the session's working directory, so start Claude Code inside the repo you want to analyze; see Setup for the other supported overrides.

Per-Client Config

The JSON shape is the same across MCP clients (VS Code uses a top-level "servers" key); only the config file path differs. See the compatibility matrix for per-client paths and a health-check prompt, and docs/mcp-json-examples/ for copy-ready snippets.

Live Surface

The current release exposes 171 tools (110 stable / 61 experimental), 14 resources (9 stable / 5 experimental), and 20 prompts (all experimental).

Use the running server for the authoritative live catalog and support tiers:

server_info for a human-readable summary
roslyn://server/catalog for the machine-readable contract
roslyn://server/resource-templates for resource URI templates

Stable families include workspace/session management, semantic navigation, diagnostics, build/test helpers, and preview/apply refactoring flows. Experimental families include broader project mutation, scaffolding, orchestration, direct text-edit helpers, and prompts. Set ROSLYNMCP_TOOL_TIERS=stable to register only the closed stable workflow (currently 91 callable tools) for clients that eagerly load tool definitions.

Configuration And Security

All operational settings are optional ROSLYNMCP_* environment variables with compiled-in defaults; the full reference is in docs/setup.md. The exception is ROSLYNMCP_SANCTIONED_ROOTS, which you must set (see above).

Loading a solution or project executes MSBuild evaluation: only load repositories you trust, or run the server in a sandbox. The filesystem boundary is server-owned; a client's MCP Roots can only narrow it. See docs/setup.md and SECURITY.md for the disclosure policy. Upgrading from 2.x? Read the migration notes first.

Docs

docs/README.md — index of everything under docs/
docs/setup.md — packaging, install options, configuration, security model, plugin install, CI artifacts
docs/compatibility.md — MCP client compatibility matrix and health check
docs/stdio-client-integration.md — custom MCP client integration
docs/product-contract.md — stable vs experimental surface contract
docs/release-policy.md — release gates and compatibility rules
CONTRIBUTING.md — build from source, tests, and filing surface-test findings
AGENTS.md — bootstrap entry point for AI agents working in this repo
ai_docs/README.md — canonical AI-doc routing index

Support

Bugs and feature requests: GitHub Issues
Contribution guidelines: CONTRIBUTING.md
Security disclosures: SECURITY.md

Roslyn MCP

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

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

ScienceShot science reference

README from the maker

Roslyn-Backed MCP Server

Quick Start

Option A — Install As A Global Tool

Option B — Zero-Install Via dnx (.NET 10)

Option C — Claude Code Plugin

Per-Client Config

Live Surface

Configuration And Security

Docs

Support

Option B — Zero-Install Via `dnx` (.NET 10)