resharper-cli-mcp

resharper-cli-mcp is an MCP server that runs JetBrains' ReSharper command-line tools and exposes them to C# coding agents over stdio. It is unofficial — not affiliated with or endorsed by JetBrains.

It gives an agent two things a text search cannot: a real ReSharper inspection of your solution (resharper_inspect), and ReSharper's own code cleanup applied in place (resharper_cleanup). The server shells out to a jb you install yourself, and bundles no JetBrains software.

Quickstart

The server needs the .NET 10 SDK and JetBrains' ReSharper Command Line Tools. Both install as .NET global tools, and neither needs an IDE.

dotnet tool install -g JetBrains.ReSharper.GlobalTools
dotnet tool install -g Zphil.ReSharperCli

Register the server with your MCP client under the command resharper-cli-mcp. For Claude Code, add it to .mcp.json:

{
  "mcpServers": {
    "resharper": {
      "command": "resharper-cli-mcp"
    }
  }
}

The server finds a single .sln/.slnx in its working directory. When that directory holds zero or several, set JB_SOLUTION_PATH in the config's env block or pass solutionPath on the call.

VS Code and Cursor users can add the server in one click, once both tools are installed:

Install as a Claude Code plugin

Claude Code users can install everything in one step instead of editing .mcp.json by hand. This repository doubles as a single-plugin marketplace, so the two tools, the derive_style_guide prompt, and both guide resources — resharper://guides/configuration for what ReSharper enforces and resharper://guides/setup for running the server — arrive together:

/plugin marketplace add andypgray/resharper-cli-mcp
/plugin install resharper-cli-mcp@resharper-cli-mcp

The plugin starts the server with dotnet dnx, which fetches Zphil.ReSharperCli from NuGet on first use — so you skip dotnet tool install for the wrapper itself. You still need the .NET 10 SDK and JetBrains' ReSharper Command Line Tools (dotnet tool install -g JetBrains.ReSharper.GlobalTools), which this project never bundles. ReSharper's caches live in the plugin's own data directory, outside your source tree.

Tools

Scope resharper_inspect with the files glob and raise severity (Suggestion, Warning, Error; default Warning) to control how much comes back. Each issue carries a file, line, severity, rule ID, and message:

Found 2 issue(s) across 1 file(s):

### /repo/src/HomeController.cs
- **Line 8** [WARNING] `RedundantUsingDirective`: Using directive is not required by the code and can be safely removed.
- **Line 24** [SUGGESTION] `FieldCanBeMadeReadOnly.Local`: Field can be made readonly.

A solution-wide run comes back more compactly: once it would overflow the output budget, issues repeating a rule within a file collapse to a single line — - **`NotAccessedPositionalProperty.Global`** [WARNING] x30, lines 13-42 — so the count stays exact and every line number is still there. See Configuration for the rest of that ladder.

Call resharper_cleanup once, at the end of a task, with every file you changed batched into the one call.

The first run on a solution is slow while ReSharper builds its caches under --caches-home; later runs reuse them and finish in seconds. The server caps each run at 5 minutes.

To spend that cold run on idle time rather than yours, the server starts one speculative inspection of the discovered solution as soon as a client connects — at most once per session, skipped when any run against that cache succeeded in the last hour, and silently skipped entirely when there is no solution to find. A real call arriving mid-pre-warm cancels it and takes the cache, so it never queues behind one in the same server process; one running in another process cannot be cancelled and is the one case where a first call can be slower than before. It is a full solution analysis, which is not free — set RESHARPER_MCP_PREWARM=off to turn it off.

Calls against one solution are serialized, across every client on the machine: only one jb at a time can use a solution's cache, and a second one that tries silently forks a cold copy instead of waiting — so two sessions inspecting one solution would otherwise make each other slow and leave a stale cache behind. A call therefore waits up to 5 minutes for a run already in flight before starting its own 5-minute run, and says so if that wait runs out. If your MCP client's own tool-call timeout is shorter than a cold run needs, the client gives up first. In Claude Code, raise it with a per-server "timeout" in milliseconds in .mcp.json, or the MCP_TOOL_TIMEOUT environment variable.

Configuration

Set these in the MCP client config's env block. All are optional.

The solutionPath tool argument overrides JB_SOLUTION_PATH for a single call. When a result would exceed MAX_MCP_OUTPUT_TOKENS (2.5 characters per token, or 25,000 characters when unset), both tools re-render it at progressively lower detail until it fits, then append a DETAIL REDUCED note naming the level and what that level gave up. Inspection steps down five: every issue listed, then repeated rules collapsed per file, then only the eight most-affected files listed, then a rules-and-files rollup, then a one-line summary. Every issue is still counted and every file still named at each step — a reduced result is complete but less detailed, unlike a truncated one. Truncation at a line boundary remains only as a last-resort backstop for when even the one-line summary overflows.

Solution discovery tries, in order: the solutionPath argument, then JB_SOLUTION_PATH, then a single .sln/.slnx in the working directory (top level only, no parent walk). Zero or several without an override is an error that names the variable to set.

Settings discovery tries, in order: JB_SETTINGS_PATH (a missing file logs a warning and falls through), then a .DotSettings file beside the solution, then GlobalSettingsStorage.DotSettings in the JetBrains shared directory, then none. On top of whichever it finds, jb also reads .editorconfig from the source tree automatically — no flag needed — so editorconfig style rules apply even with no .DotSettings at all.

Logs roll daily under %LOCALAPPDATA%\Zphil.ReSharperCli\logs on Windows, and the platform-equivalent path elsewhere. Nothing leaves the machine; PRIVACY.md states that as policy.

Deriving a style guide for a legacy codebase

Adding this server to a large existing solution unlocks a second workflow: deriving an intentional ReSharper style guide from the code you already have, so an inspection flags real house-style deviations rather than un-configured defaults. The server advertises an MCP prompt, derive_style_guide (surfaced as a slash command or prompt-picker entry in clients that render prompts), that walks an agent through it.

Be clear on the division of labour: ReSharper's command-line tools have no "infer settings from code" verb, and this server does not infer settings. The agent derives the rules from evidence — the code plus whatever is already in the repo (StyleCop, analyzers, an existing .editorconfig) — and resharper_inspect validates them: scope an inspection to a representative folder, then keep or silence each noisy rule until the remaining output is all intentional. The recipe is .editorconfig-first (portable across ReSharper, StyleCop.Analyzers, Roslyn, dotnet format, and Rider), spilling only ReSharper-only knobs and cleanup-profile definitions into .sln.DotSettings. When the codebase genuinely mixes conventions, the prompt pauses and asks rather than guessing.

If a teammate has ReSharper or Rider, prefer JetBrains' first-party Detect Code Style Settings for the baseline; it is IDE-only, so this recipe is the path for headless, CI, or no-licence use, and it adds StyleCop reconciliation and severity tuning on top. See also ReSharper's Use EditorConfig and the InspectCode / CleanupCode references. The embedded prompt is the full recipe; this section is only a digest of it.

Cleanup is cosmetic

resharper_cleanup never changes behavior. Its fallback Built-in: Full Cleanup profile fixes formatting and style only, so an agent should write correct logic and let the cleanup pass handle the polish. There is no need to re-inspect or rebuild after it. That profile handles all of these:

• unused usings, sorted and shortened qualified references
• indentation, spacing, line breaks, and wrapping
• var versus explicit type, per the solution's settings
• modifier order, and explicit or implicit modifiers as configured
• redundant parentheses, this. qualifiers, casts, and default values
• braces around single statements, per style
• auto-properties, readonly fields, object-creation style, trailing commas, namespace style

Keep the agent's editing effort on logic, types, naming, and architecture. For a legacy codebase where Full Cleanup would churn regions you did not touch — or for a deliberate style it would normalize away — define a narrower profile (for example Custom: No Reordering) in the solution's .sln.DotSettings. Name it under SilentCleanupProfile there and every call uses it without a profile argument, including calls from an agent that does not know it exists; the profile argument overrides it per call.

resharper_cleanup reports which of the files it changed on disk, so an agent can see when a cleanup rewrote something it meant to leave alone rather than trusting a bare "completed". A small batch lists every file; a solution-wide run collapses the per-file detail toward counts to stay within the output budget.

Configuring what ReSharper enforces

The two tools read two independent configuration axes: resharper_inspect obeys inspection severities (what gets reported), and resharper_cleanup enforces code style through its cleanup profile (what gets rewritten). They do not share a switch — setting a rule to DO_NOT_SHOW hides its inspection issue but does not stop cleanup from normalizing that style. Some styles are binary with no "leave alone" value (argument style is positional or named), so protecting one means narrowing the profile, excluding the file, or an in-source // ReSharper disable comment.

Rather than carry that model in every session's context, the server advertises it as an on-demand MCP resource, resharper://guides/configuration — the two axes, how to protect a deliberate style, where settings and .editorconfig are read from, and the .DotSettings key shapes. A client that surfaces resources lets an agent load it exactly when it is about to change what ReSharper enforces.

A second resource, resharper://guides/setup, covers running the server rather than configuring ReSharper: how jb and the solution are discovered, why the first call is slow and what the background pre-warm does about it, what the 5-minute caps mean and why calls against one solution queue, how a large result is shortened to fit the output budget, the environment variables above, and where logs go. An agent loads it when a call cannot find jb or the solution, times out, or comes back shortened. Splitting the two keeps each pull small, and keeps the always-loaded server instructions down to the cross-tool rules that no schema can express.

Cleanup reminder hook

The single end-of-task cleanup above is easy for an agent to forget. A Claude Code PostToolUse hook can nudge it toward the habit without running anything itself. Add this to .claude/settings.json:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Edit|Write",
        "hooks": [
          {
            "type": "command",
            "command": "grep -qiE '\"file_path\"[[:space:]]*:[[:space:]]*\"[^\"]*\\.(cs|razor)\"' && printf '%s' '{\"hookSpecificOutput\":{\"hookEventName\":\"PostToolUse\",\"additionalContext\":\"When this task is done, batch every edited .cs/.razor file into one resharper_cleanup call.\"}}' || true"
          }
        ]
      }
    ]
  }
}

After each .cs/.razor edit the hook adds a one-line reminder to the agent's context; on any other file it prints nothing and does nothing. It never edits code or calls the tool, so the agent decides when to clean up. The command uses grep and printf, so it needs a POSIX shell (on Windows, Git Bash).

Contributing

Contributions are welcome. Bug reports reproduced on a public solution, MCP client-compatibility fixes, and improvements to discovery or output formatting land best. See CONTRIBUTING.md for the development setup (.NET 10 SDK) and the two-seam test architecture. To report a security issue privately, see SECURITY.md.

License

MIT; see LICENSE.

JetBrains and ReSharper are trademarks of JetBrains s.r.o. This project is an independent wrapper of their ReSharper Command Line Tools, which ship under JetBrains' own license.