C# Class Analyzer MCP server

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CSharpAnalyserMcp

A read-only Model Context Protocol (MCP) server that lets an AI assistant browse any C# solution through Roslyn.

The server loads a solution with MSBuildWorkspace into a cached Roslyn snapshot and then answers structured queries about it: where each type is declared, its XML documentation, and a method's signature, documentation, source location and body. An agent can therefore pull in the exact slice of source it needs instead of reading whole files into its context window.

• Transport: stdio (StdioServerTransport), protocol traffic on stdout only; all logs go to stderr.
• Solution path is passed on the command line (--workspace ); the solution is loaded before the MCP handshake, so a bad path fails fast with a message on stderr and a non-zero exit code.
• Tools declare structured output (UseStructuredContent), so results arrive as MCP structuredContent with camelCase JSON fields.
• Distribution: published to NuGet as the .NET tool CSharpAnalyserMcp (command csharp-analyser-mcp) and listed in the official MCP Registry as io.github.undy-mosq/CSharpAnalyserMcp.

Installation

NuGet .NET tool (recommended)

dotnet tool install --global CSharpAnalyserMcp
csharp-analyser-mcp --workspace D:\MyProject\MySolution.sln

# upgrade / remove
dotnet tool update --global CSharpAnalyserMcp
dotnet tool uninstall --global CSharpAnalyserMcp

Install it globally: a --local install only writes a manifest entry, so csharp-analyser-mcp never lands on PATH and MCP clients cannot start it.

On demand with dnx (nothing to install, .NET SDK 10+)

# "--" separates dnx options from the arguments forwarded to the server
dnx CSharpAnalyserMcp --yes -- --workspace D:\MyProject\MySolution.sln

From source

git clone https://github.com/undy-mosq/CSharpAnalyserMcp
dotnet build CSharpAnalyserMcp\CSharpAnalyserMcp.csproj
dotnet run --project CSharpAnalyserMcp -- --workspace D:\MyProject\MySolution.sln

Requirements

Client configuration

The server is started with a single argument, --workspace, pointing at the solution file.

Installed .NET tool

The global tool shim lives in %USERPROFILE%\.dotnet\tools. MCP clients spawn the process themselves and only see the PATH they inherited, so point the configuration at the shim by absolute path (expand %USERPROFILE%, e.g. C:\Users\you\.dotnet\tools\csharp-analyser-mcp.exe):

Claude Desktop (claudedesktopconfig.json):

{
  "mcpServers": {
    "csharp-analyser": {
      "command": "C:\\Users\\you\\.dotnet\\tools\\csharp-analyser-mcp.exe",
      "args": ["--workspace", "D:\\MyProject\\MySolution.sln"]
    }
  }
}

VS Code (.vscode/mcp.json):

{
  "servers": {
    "csharp-analyser": {
      "type": "stdio",
      "command": "C:\\Users\\you\\.dotnet\\tools\\csharp-analyser-mcp.exe",
      "args": ["--workspace", "D:\\MyProject\\MySolution.sln"]
    }
  }
}

The bare command name ("command": "csharp-analyser-mcp") works only when that directory is already on the client's PATH; a client started before the tool was installed keeps the old environment, so restart it after changing PATH.

On demand with dnx (nothing installed)

Shortened. The full README is on GitHub.