Filesystem server fails with directory paths containing spaces

[DesignerFatih]

Describe the bug
MCP filesystem server fails to properly handle directory paths containing spaces when specified in claude_desktop_config.json.

To Reproduce
Steps to reproduce the behavior:

1. Configure Claude Desktop with the following claude_desktop_config.json:

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "D:\\FACE",
        "D:\\WORKING\\00_PROJECT",
        "D:\\DEV DB"
      ]
    }
  }
}

Restart Claude Desktop
Try to access files in the D:\\DEV DB directory
Only the first two directories (without spaces) are accessible

Expected behavior
All three directories should be accessible via MCP, including the one with spaces (D:\\DEV DB).
Logs
The filesystem server starts successfully but the directory with spaces is not recognized as an allowed directory.
Additional context

OS: Windows 11 Turkish
Node JS v22.17.1
Claude 0.12.55 (d55c63) 2025-07-25T17:43:32.000Z
Workarounds attempted:

Tried wrapping path in double quotes: "\"D:\\DEV DB\""
Tried single quotes: "'D:\\DEV DB'"
Both approaches failed


The issue appears to be in argument parsing where spaces in paths are not properly handled
This affects Windows users more commonly due to default folder naming conventions (like "Program Files", "Documents and Settings", etc.)

Edit:

Further testing with various new and existing directory names confirmed that this issue only occurs with paths containing spaces. All other non-space-containing paths are processed correctly.

[DesignerFatih]

Hi!

Bug Report Draft for Claude Desktop server-filesystem Issue

Issue Title: server-filesystem with npx fails with "Server disconnected" on Windows paths containing spaces.

Description:

When attempting to launch the @modelcontextprotocol/server-filesystem server through Claude Desktop, configured via claude_desktop_config.json under mcpServers, the server fails with a "Server disconnected" error if the specified root directory path contains spaces (e.g., D:\DEV DB, C:\TEST KLASOR). This indicates that the server is likely unable to correctly process the directory path when spaces are present.

Environment:

Operating System: Windows 11 (Turkish UI)

Claude Desktop Version: Approximately 0.12.55 (derived from app-0.12.55 folder name)

@modelcontextprotocol/server-filesystem Version: 0.6.2

Node.js Version: (As used by Claude Desktop's embedded environment)

Development Environment: VS Code

File System Structure:

    servers project root: D:\CODING\GitHub\servers

    server-filesystem source code: D:\CODING\GitHub\servers\src\filesystem

Problem Details:

When a root directory path containing spaces (e.g., "D:\DEV DB") is specified in claude_desktop_config.json, the server-filesystem process launched by Claude Desktop exits unexpectedly. The error message in Claude Desktop's UI shows: Command: npx, Arguments: -y @modelcontextprotocol/server-filesystem D:\CODING D:\WORKING\00_PROJELER D:\LOGSEQ_DB C:\TEST KLASOR, followed by Error: Server disconnected.

Identified Root Cause (Probable):

The core issue is likely within the path comparison logic in the isPathWithinAllowedDirectories function located in src/path-validation.ts of the @modelcontextprotocol/server-filesystem package. Initially, this function used a string comparison: normalizedPath.startsWith(normalizedDir + path.sep). On Windows, discrepancies in how path.normalize() or path.resolve() handle paths with spaces or trailing slashes could cause this string comparison to fail.

Attempted Solutions and Outcomes:

Code Modification in src/path-validation.ts:

    The path comparison logic within the isPathWithinAllowedDirectories function was modified to use the more robust path.relative() function. This included ensuring consistent path formatting (adding path.sep to directory paths for comparison) and validating path.relative()'s output (ensuring it doesn't start with .. or is an absolute path).

    Direct use of path.resolve(absolutePath) was preferred over path.resolve(path.normalize(absolutePath)) for simplicity and consistency.

    Result: The code change was successfully implemented and the package was built using npm run build.

Attempts to Reflect Changes in Claude Desktop via npm link:

    Objective: To replace Claude Desktop's default @modelcontextprotocol/server-filesystem with the locally modified and built version for testing.

    Initial npm link (Source package): Executed npm link in the source directory D:\CODING\GitHub\servers\src\filesystem. This successfully created a global symlink for the package.

    Locating Claude Desktop's node_modules: Significant effort was made to identify where Claude Desktop stores its Node.js dependencies.

        Common system-wide paths (e.g., C:\Users\<UserName>\AppData\Local\Programs\Claude\resources\app or C:\Program Files\Claude\resources\app) were checked but found to be non-existent.

        The main installation directory C:\Users\<UserName>\AppData\Local\AnthropicClaude was identified.

        Further investigation revealed an app-0.12.55\resources folder, and then app-0.12.55\resources\app.asar.unpacked\node_modules containing a .node file, suggesting ASAR archiving.

        asar list app.asar was attempted to inspect the ASAR archive contents, but the asar command itself wasn't directly found in the PATH, requiring troubleshooting for asar command execution.

        Crucial Discovery: The actual global location where npx resolves @modelcontextprotocol/server-filesystem was found to be C:\Users\benna\AppData\Roaming\npm\node_modules\@modelcontextprotocol\server-filesystem.

    Second npm link Attempt (Target package): Executed npm link @modelcontextprotocol/server-filesystem within the discovered global npm node_modules directory (C:\Users\benna\AppData\Roaming\npm\node_modules\@modelcontextprotocol\server-filesystem).

    Outcome: This npm link command failed with TypeScript compilation errors, specifically error TS5083: Cannot read file 'C:/Users/benna/AppData/Roaming/npm/node_modules/tsconfig.json'. and a type incompatibility error (TS2345). This indicates that npm link was attempting to re-build the package at the target location and failed to find necessary tsconfig.json or encountered type definition conflicts in that context.

Open Issues and Further Steps:

The primary challenge remains making Claude Desktop use the locally modified and built version of the server-filesystem package. The npm link process does not seem to behave as expected when dealing with the global npm installation's package directory.

The TypeScript compilation errors (TS5083 and TS2345) suggest an issue with tsconfig.json resolution or conflicting type definitions (possibly related to diff library usage) when npm link attempts an implicit build.

As a potential next step (though temporary): Manually copying the contents of the dist folder from the local, built server-filesystem project (D:\CODING\GitHub\servers\src\filesystem\dist) into the Claude Desktop's expected package location (C:\Users\<UserName>\AppData\Roaming\npm\node_modules\@modelcontextprotocol\server-filesystem) could be attempted. However, this is not an ideal solution as it would require manual re-copying after every code change or update.

A deeper investigation into the overall package.json structure of the @modelcontextprotocol/servers monorepo and how npx resolves dependencies within the Electron application might be necessary to find a robust solution.

[sebastien-rosset]

I think this was fixed by #543