MCP /mcp reconnect fails with code-mode server

[mark-software]

Description

The /mcp command fails to reconnect to a code-mode MCP server with the error:

Failed to reconnect to code-mode.

This happens even after restarting Claude Code. However, the underlying MCP server works perfectly when run manually from the terminal.

Environment

• Claude Code version: 2.1.15 (also tested behavior persists after restart)
• macOS Darwin 24.6.0
• Node.js (npx works fine)

MCP Configuration

.mcp.json:

{
  "mcpServers": {
    "code-mode": {
      "command": "npx",
      "args": ["@utcp/code-mode-mcp"],
      "env": {
        "UTCP_CONFIG_FILE": "/path/to/.utcp_config.json"
      }
    }
  }
}

The code-mode server proxies to remote MCP servers (Supabase, Cloudflare) via mcp-remote.

Reproduction Steps

1. Configure code-mode MCP server as shown above
2. Start Claude Code - MCP may or may not connect initially
3. Run /mcp to try to reconnect
4. Observe "Failed to reconnect to code-mode" error

What Works

Running the server manually works fine:

npx @utcp/code-mode-mcp

Output shows successful connections:

• Supabase: 20 tools discovered
• Cloudflare observability: 10 tools discovered
• Cloudflare bindings: 25 tools discovered

OAuth tokens are valid and fresh. No stale processes blocking.

Expected Behavior

/mcp should successfully reconnect to the code-mode server, or provide a more descriptive error message about what's failing.

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] GitLab MCP plugin fails to reconnect - "Failed to reconnect to plugin:gitlab:gitlab" #17209
2. [BUG] /mcp command doesn't display stderr output from failed MCP server connections #17950
3. Windows: claude mcp add mangles /c flag, breaks npx-based MCP servers #20061

This issue will be automatically closed as a duplicate in 3 days.

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🤖 Generated with Claude Code

[github-actions]

This issue has been automatically closed as a duplicate of #17209.

If this is incorrect, please re-open this issue or create a new one.

🤖 Generated with Claude Code

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.