Namespace Built-in MCP Extensions to Avoid User Config Collisions

[Im-Hal-9K]

Pre-submission Checklist

• I have verified this would not be more appropriate as a feature request in a specific repository
• I have searched existing discussions to avoid duplicates

Your Idea

Feature Request: Namespace Built-in MCP Extensions to Avoid User Config Collisions

Summary

Built-in MCP extensions in Claude Desktop should use a namespaced naming convention (e.g., claude:filesystem or builtin:filesystem) to prevent collisions with user-defined MCP servers in claude_desktop_config.json.

Current Behavior

Claude Desktop includes built-in MCP extensions like Filesystem. When a user creates a custom MCP server with the same or similar name (filesystem, Filesystem), the following problems occur:

1. Duplicate entries appear in the available tools list
2. Wrong server executes - Claude Desktop may use the built-in instead of the user's custom config
3. Immediate crashes - The built-in extension crashes after initialization with "Server transport closed unexpectedly"
4. Confusing debugging - Log files show both [filesystem] and [Filesystem] entries, making it unclear which is running

Log Evidence

2025-11-27T05:46:29.617Z [Filesystem] [info] Using built-in Node.js for MCP server: Filesystem
2025-11-27T05:46:29.644Z [Filesystem] [info] Server started and connected successfully
2025-11-27T05:46:29.766Z [Filesystem] [info] Server transport closed unexpectedly...
2025-11-27T05:46:29.766Z [Filesystem] [error] Server disconnected.

The user's custom config was ignored in favor of the built-in, which then crashed.

Current Workaround

Users must avoid naming their custom MCP servers anything that matches built-in extension names. This is undocumented and requires trial-and-error discovery.

{
  "mcpServers": {
    "localfiles": { ... }
  }
}

Proposed Solution

Namespace all built-in MCP extensions to clearly distinguish them from user-defined servers:

Option A: Prefix with claude:

claude:filesystem
claude:google-drive
claude:google-calendar

Option B: Prefix with builtin:

builtin:filesystem
builtin:google-drive
builtin:google-calendar

Option C: Use @anthropic/ package-style naming

@anthropic/filesystem
@anthropic/google-drive
@anthropic/google-calendar

Benefits

1. No collisions - User configs can use natural names like filesystem without conflict
2. Clear distinction - Easy to tell built-in vs custom in logs and UI
3. Better debugging - Log entries unambiguous
4. Documentation simplification - No need to maintain list of "reserved names"
5. Future-proof - As more built-in MCPs are added, collision risk grows

Additional Suggestion

If namespacing isn't implemented, at minimum:

• Document the reserved names that users should avoid
• Add a warning when user config name matches a built-in
• Prioritize user config over built-in when names match (user intent is clear)

Environment

• Claude Desktop 1.0.1217
• Windows 11
• Issue discovered while debugging GitHub Issue (path space handling) filesystem MCP server doesn't support legal Windows pathnames in claude_desktop_config.json servers#447

Scope

• Protocol Specification
• SDK Features
• Documentation
• Developer Experience
• Other