Fails to load in Claude Code

[aaearon]

Describe the bug
The MCP server does not load when running with Claude Code. gemini-cli is installed and authenticated.

[
  {
    "debug": "Starting connection attempt",
    "timestamp": "2025-07-14T16:05:12.146Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "debug": "Connection failed: McpError: MCP error -32000: Connection closed",
    "timestamp": "2025-07-14T16:05:12.623Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "debug": "Error message: MCP error -32000: Connection closed",
    "timestamp": "2025-07-14T16:05:12.624Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "debug": "Error stack: McpError: MCP error -32000: Connection closed\n    at ka1._onclose (file:///C:/Users/Tim/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1336:15216)\n    at _transport.onclose (file:///C:/Users/Tim/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1336:14535)\n    at ChildProcess.<anonymous> (file:///C:/Users/Tim/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1338:1459)\n    at ChildProcess.emit (node:events:518:28)\n    at ChildProcess.emit (node:domain:489:12)\n    at LbQ.A.emit (file:///C:/Users/Tim/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:320:155823)\n    at maybeClose (node:internal/child_process:1101:16)\n    at Socket.<anonymous> (node:internal/child_process:456:11)\n    at Socket.emit (node:events:518:28)\n    at Socket.emit (node:domain:489:12)",
    "timestamp": "2025-07-14T16:05:12.627Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "error": "Connection failed: MCP error -32000: Connection closed",
    "timestamp": "2025-07-14T16:05:12.631Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "debug": "Connection attempt completed in 486ms - status: failed",
    "timestamp": "2025-07-14T16:05:12.633Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "debug": "Starting connection attempt",
    "timestamp": "2025-07-14T16:05:13.321Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "debug": "Connection attempt completed in 73ms - status: failed",
    "timestamp": "2025-07-14T16:05:13.395Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "debug": "Starting connection attempt",
    "timestamp": "2025-07-14T16:05:14.823Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  },
  {
    "debug": "Connection attempt completed in 22ms - status: failed",
    "timestamp": "2025-07-14T16:05:14.845Z",
    "sessionId": "b0ab4666-a02e-4050-a930-198a7d882436",
    "cwd": "C:\\Users\\Tim\\Projects\\vault-migrator-tool"
  }
]

C:\Users\Tim\Projects\vault-migrator-tool>claude mcp list
gemini-cli: npx -y gemini-mcp-tool

To Reproduce
Steps to reproduce:

1. Add mcp server via claude mcp add gemini-cli -- npx -y gemini-mcp-tool in project directory
2. Start claude and server fails to start.

Expected behavior
It should start

Environment:

• Node version: v22.15.1
• OS: Windows 11
• MCP client: Claude Code

[vikas-shopos]

For temporary workaround, you can install globally bun install -g gemini-mcp-tool and then install in CC claude mcp remove gemini-cli

[aaearon]

Unfortunately this did not work for me.

[vikas-shopos]

@aaearon do this

1. Remove claude mcp remove gemini-cli
2. Install Global: npm install -g gemini-mcp-tool
3. Add MCP : claude mcp add gemini-cli -s user gemini-mcp

[bukanpeneliti]

@aaearon do this

1. Remove claude mcp remove gemini-cli
2. Install Global: npm install -g gemini-mcp-tool
3. Add MCP : claude mcp add gemini-cli -s user gemini-mcp

I can confirm this also doesn't work.

• Node: v22.17.0
• claude code version: 1.0.53

Edit:
here's the claude code output:

/gemini-cli:ping (MCP) is running…

● I see you tested the gemini-cli MCP integration and it's working
correctly. The /gemini-cli:ping command returned "Pong!" which confirms
the connection is established.

Is there something specific you'd like me to help you with regarding
your BI project or any other task?

/gemini-cli:help (MCP) is running…

● The gemini-cli MCP integration is configured but the gemini command
isn't found in your system PATH. You need to install the Gemini CLI
tool.

To install it, run:
npm install -g @google/generative-ai-cli

Or if you prefer using a different package manager:
yarn global add @google/generative-ai-cli

After installation, you'll need to authenticate with your Google AI API
key.

[MiguelMachado-dev]

@aaearon do this

1. Remove `claude mcp remove gemini-cli`

2. Install Global: `npm install -g gemini-mcp-tool`

3. Add MCP : `claude mcp add gemini-cli -s user gemini-mcp`

This is not working for me either.
Using fnm 1.38.1 on Windows 11.

• Node: v24.0.2
• Claude Code: 1.0.53
• gemini: 0.1.12

[dinhphieu]

It doesn't work for me either, getting:

● I'll help you scan the codebase using Gemini. Let me use the Gemini CLI tool to analyze the project structure and provide an overview of the codebase.

● gemini-cli - ask-gemini (MCP)(prompt: "Please scan and analyze the entire codebase structure. Focus on:\n1. Overall project architecture and organization\n2. Key packages and their purposes (server, cli, engine)\n3. Technology stack and
                               frameworks used\n4. Build system and dependencies\n5. Testing approach\n6. Authentication and database architecture\n7. Any notable patterns or conventions\n\n@packages/server/**/*.ts @packages/cli/**/*.ts
                               @packages/engine/**/*.ts @package.json @tsconfig.json @CLAUDE.md")
  ⎿  Error: Failed to spawn command: spawn gemini ENOENT    

[jamubc]

I'm working on this, just been slow testing large edits 🥲

[Adrien2u]

I'M NOT A CODER, PERIOD. AND, YES, CLAUDE WROTE THIS, BUT I WANTED THIS MCP & CLAUDE ADVISED ME TO SHARE. I DO WHAT CLAUDE ASKS

🔧 Windows Compatibility Fix + @ File Syntax Guide

I've identified and successfully tested a solution for this Windows "Connection closed" error, plus discovered critical usage patterns for the @ file syntax that will help all users.

Root Cause Analysis

The issue is in src/index.ts at line 669 in the executeCommand() function. The child_process.spawn() call lacks the shell: true option that Windows requires, causing ENOENT errors when trying to execute the gemini command.

Solution

File: src/index.ts
Line: 669
Change: Add Windows-specific shell mode to spawn options

const result = spawn(command, args, {
  cwd: process.cwd(),
  shell: process.platform === 'win32', // Add this line for Windows compatibility
  stdio: ['inherit', 'pipe', 'pipe'],
  env: process.env
});

Testing Results ✅

• Environment: Windows 11, Node.js v22.15.1, Claude Code
• Status: All MCP tools now working perfectly
• Tools Verified: ask-gemini, sandbox-test, Ping, Help
• Feature Restored: @ file syntax for large file analysis

📚 Critical @ File Syntax Usage (Discovered During Testing)

✅ CORRECT Usage:

Tool: gemini-cli:ask-gemini
Prompt: @package.json

❌ INCORRECT Usage (Causes Errors):

@package.json explain this file     ❌ Causes "Unknown arguments" error
@src/index.ts analyze functions     ❌ Will fail
@README.md what does this do        ❌ Parsing error

Proper Workflow:

1. Load file: @filename.ext (alone in prompt)
2. Get analysis: Gemini automatically analyzes the file
3. Follow-up: Ask specific questions in separate prompt

File Type Examples:

@package.json           # Node.js configuration
@src/index.ts          # TypeScript source files
@README.md             # Documentation
@webpack.config.js     # Build configurations
@data/users.csv        # Data files
@dist/bundle.js        # Built/compiled files

Impact

This one-line fix resolves the Windows spawn ENOENT errors completely while preserving Unix/Linux compatibility. The @ file syntax is now working perfectly for analyzing large files and codebases - the core feature that makes this tool so powerful.

Verification Steps

1. Applied fix to line 669 in src/index.ts
2. Rebuilt project with npm run build
3. Updated Claude Desktop configuration to use local build
4. Tested all four MCP tools successfully
5. Verified @ file syntax works with various file types
6. Documented proper usage patterns to prevent common errors

I'd be happy to create a pull request with this fix and usage documentation if helpful. This should resolve the issue for Windows users immediately and help everyone use the @ file syntax correctly.

[jamubc]

Noted the above Claude fix👍🏻 will address feel free to pull if you have time.

[alexx-ftw]

Noted the above Claude fix👍🏻 will address feel free to pull if you have time.

I did in pr #17 along with other goods-to-have

[jamubc]

Issue has been resolved in 1.1.5.

Thanks for your contributions @alexx-ftw and others here.