Roslyn CodeLens MCP Server

A Roslyn-based MCP server that gives AI agents deep semantic understanding of .NET codebases - type hierarchies, call graphs, DI registrations, diagnostics, refactoring, and more. It runs locally over stdio via the published package.

People connecting coding agent tools to Claude, Cursor, VS Code, or another MCP client. The project is written in C#.

VERIFIED ACTIVE

LAST COMMIT 2026-08-22 · ★ 48 · #32 OF 194 MAINTAINED CODING AGENT · VERIFIED 2026-08-25

MIT · C# · how we verify → /methodology

01 · Install Roslyn CodeLens

Claude Code

claude mcp add marcelroozekrans-roslyn-codelens-mcp -- npx -y roslyn-codelens-mcp

Claude Desktop / Cursor / VS Code - add to config

{
  "mcpServers": {
    "marcelroozekrans-roslyn-codelens-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "roslyn-codelens-mcp"
      ]
    }
  }
}

Same JSON for Cursor. For VS Code, rename the top-level key from `mcpServers` to `servers`.

Using another client? Same JSON, different key

Claude Desktop · mcpServers

Cursor · mcpServers

VS Code · servers

Windsurf · mcpServers

Zed · context_servers

Cline · mcpServers

Roo Code · mcpServers

Continue · mcpServers

LibreChat · mcpServers

Gemini CLI · mcpServers

Codex CLI · mcp_servers

Full setup guides: every client.

02 · Evidence

Security posture

What to check before giving this server access to your agent - from the registry, GitHub, and our own probes. We don't score safety; we show what's verifiable.

runs as local process (stdio) - runs on your machine with your user's permissions

license MIT - declared in the repository

npm package roslyn-codelens-mcp - unscoped; check the name against the project README before installing

registry namespace io.github.MarcelRoozekrans is GitHub-verified and matches the repo owner

03 · What Roslyn CodeLens can do

Prose above is summarized from the project's README and registry record - no invented capabilities.

Latest releases

v2.18.0 · 2026-08-21

2.18.0 (2026-08-21) · attribute generated-code results to their authored markup · resolve generated-code blind spots surfaced by #399 · run the SDK's source generators by matching its Roslyn version (#399)

v2.17.0 · 2026-08-14

2.17.0 (2026-08-14) · add streamable HTTP transport behind --http flag

v2.16.2 · 2026-08-12

2.16.2 (2026-08-12) · let contributors opt out of ZeroAlloc.Analyzers (#376) (77502c2), closes #369

04 · Who maintains Roslyn CodeLens

Roslyn CodeLens is maintained by marcelroozekrans. We track 2 MCP servers from marcelroozekrans - 2 actively maintained, 58 combined GitHub stars, oldest repo from Mar 2026. Full record: all servers from marcelroozekrans.

memorylens-mcp MCP server for .NET memory profiling - in-process heap snapshots via EventPipe with leak heuristics ★ 10

05 · Facts

repository: github.com/marcelroozekrans/roslyn-codelens-mcp
category: coding agent - ranked #32 of 194 actively-maintained coding agent servers as of 2026-08-25.
release cadence: 10+ releases in the last 90 days (latest 2026-08-21)
registry: io.github.MarcelRoozekrans/roslyn-codelens (active, first published 2026-03-30 · 29 versions)
packages: npm:roslyn-codelens-mcp · nuget:RoslynCodeLens.Mcp

06 · Roslyn CodeLens FAQ

What is Roslyn CodeLens?

Is Roslyn CodeLens still maintained?

Yes - as of 2026-08-25, its last commit was 2026-08-22 and it shipped 10+ releases in the last 90 days. We re-verify nightly.

How do I install Roslyn CodeLens?

Run `npx -y roslyn-codelens-mcp`. You can also paste the ready-made client config above.

Does Roslyn CodeLens run locally?

Yes - it's a stdio server: it runs on your machine (via npx) with your user's permissions. Your data stays local unless the server itself calls external APIs.

07 · Alternatives to Roslyn CodeLens

Alternatives to Roslyn CodeLens

Maintained coding agent servers if Roslyn CodeLens isn't the fit.

Pairs well with

Servers that cover what Roslyn CodeLens doesn't - only shown when the pairing reason fits the companion.

More coding agent MCP servers · Sourcebook · Refactoring MCP Server · M1nd · Adrkit Decision Memory · Codebase Index