[Claude Desktop] MCP server key named "gitlab" silently fails to register tools despite successful handshake

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Note: This is a Claude Desktop bug, not Claude Code. Filing here as there is no public Claude Desktop issue tracker.

Summary

When an MCP server is configured in claude_desktop_config.json with the key name "gitlab", the server connects successfully and returns its tool list, but the tools are never registered in the conversation context. Claude reports no GitLab tools are available. Renaming the key to anything else (e.g. "gitlab_artworks") immediately fixes the issue — tools load and work perfectly.

Steps to Reproduce

1. Add an MCP server to claude_desktop_config.json with the key "gitlab":

"gitlab": {
  "command": "/path/to/mcp-gitlab",
  "args": [],
  "env": {
    "GITLAB_PERSONAL_ACCESS_TOKEN": "glpat-xxx",
    "GITLAB_API_URL": "https://gitlab.example.com/api/v4"
  }
}

1. Restart Claude Desktop
2. Verify the server shows as "running" in Settings → Developer → MCP Servers
3. Start a new conversation and try to use GitLab tools — they are not available

Expected Behavior

Tools returned by the MCP server should be registered and available in the conversation, regardless of the config key name.

Actual Behavior

• Server starts successfully (logs show Server started and connected successfully)
• Handshake completes (protocolVersion: "2025-11-25")
• tools/list returns valid tools (confirmed in ~/Library/Logs/Claude/mcp.log)
• Tools are silently not registered in the conversation context
• No error messages anywhere

Workaround

Rename the config key from "gitlab" to any other name (e.g. "gitlab_artworks", "my-gitlab", etc.). Tools load immediately.

Log Evidence

With key "gitlab" — server connects, returns tools, but they're not available:

[info] [gitlab] Server started and connected successfully
[info] [gitlab] Message from server: {"jsonrpc":"2.0","id":1,"result":{"tools":[...]}}  # 16908 chars of valid tools

With key "gitlab_artworks" — identical server, identical config, tools load and work.

Environment

• Product: Claude Desktop (macOS)
• OS: macOS (Apple Silicon)
• MCP Server: @zereight/mcp-gitlab v2.0.34
• Node: v20.18.1 / v22.19.0 (tested both)

Additional Context

The key name "gitlab" appears to be reserved or conflicts with something internal in Claude Desktop's MCP tool registration. This is a completely silent failure — no warnings, no errors — making it very difficult to diagnose. The issue persisted across multiple Claude Desktop restarts, config changes, and Node versions until the key was renamed.

What Should Happen?

Tools returned by the MCP server should be registered and available in the conversation, regardless of the config key name used in claude_desktop_config.json.

Error Messages/Logs

No errors in logs. Server connects and returns tools successfully:

[info] [gitlab] Server started and connected successfully
[info] [gitlab] Message from server: {"jsonrpc":"2.0","id":1,"result":{"tools":[...]}}  # 16908 chars of valid tools

Tools are silently not registered in the conversation context. Complete silent failure.

Steps to Reproduce

1. Add an MCP server to claude_desktop_config.json with the key "gitlab"
2. Restart Claude Desktop
3. Verify the server shows as "running" in Settings → Developer → MCP Servers
4. Start a new conversation and try to use GitLab tools — they are not available
5. Rename the key to "gitlab_artworks" (or any other name)
6. Restart Claude Desktop — tools now load and work perfectly

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.19 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Note: This is a Claude Desktop bug, not Claude Code. Filed here as there is no public Claude Desktop issue tracker.

The key name "gitlab" appears to be reserved or conflicts with something internal. Renaming to any other key (e.g. "gitlab_artworks") immediately fixes the issue. Tested with @zereight/mcp-gitlab v2.0.34 on both Node v20.18.1 and v22.19.0. The server runs perfectly when started manually — the issue is purely in Claude Desktop's tool registration.