### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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? # Bug Report: External MCP Servers Not Loading in Claude Code ## Summary Custom MCP servers configured in VS Code settings are not being loaded by

[BUG] External MCP Servers Not Loading in Claude Code

Resolved 💬 11 comments Opened Nov 21, 2025 by Barjea Closed Jan 28, 2026

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?

# Bug Report: External MCP Servers Not Loading in Claude Code

## Summary
Custom MCP servers configured in VS Code settings are not being loaded by
Claude Code extension, even after multiple VS Code restarts. The MCP server
itself works correctly when tested manually.

## Environment

OS: Ubuntu 24.04.3 LTS (Linux 6.8.0-87-generic x86_64)
VS Code Version: 1.106.2 (commit:

1e3c50d64110be466c0b4a45222e81d2c9352888)

Claude Code Extension: v2.0.49-linux-x64
Node.js Version: v20.11.0
MCP Server: claude-appsscript-pro v3.1.0
## Configuration

VS Code Settings (~/.config/Code/User/settings.json):
```json
"claude-code.mcpServers": {
"claude-appsscript-pro": {
"command": "node",
"args": ["/home/jean-louis/claude-appsscript-pro/server.js"]
}
},
"claudeCode.environmentVariables": []

claude-code-mcp-bug-report.md

What Should Happen?

Expected Behavior

The 61 tools provided by the claude-appsscript-pro MCP server should be
available in Claude Code with the prefix mcp__claude-appsscript-pro__*.
Actual Behavior

Only 2 MCP tools are available: mcp__ide__getDiagnostics and

mcp__ide__executeCode (built-in IDE tools)

None of the external MCP server tools are loaded
No error messages are shown to the user
No logs mentioning MCP or the server name in VS Code logs

Steps to Reproduce

Add custom MCP server configuration to VS Code settings.json
Restart VS Code completely (tested 3+ times)
Open Claude Code
Check available tools - only built-in IDE tools are present

Verification Steps Performed

✅ Configuration is Correct

Settings.json contains proper MCP server configuration
Server file exists at specified path
Node.js is installed and accessible

✅ MCP Server Works Independently

Manual test of the server:
cd /home/jean-louis/claude-appsscript-pro && node server.js
# Server starts successfully with no errors

❌ No Loading Attempts in Logs

# No MCP mentions in VS Code logs
grep -r "mcp" ~/.config/Code/logs/20251121T163550/
# No results

# No server name mentions
grep -r "claude-appsscript-pro" ~/.config/Code/logs/20251121T163550/
# No results

Impact

High: Users cannot use custom MCP servers despite correct configuration
Workaround exists: Using native CLI tools (like clasp for Apps Script), but

defeats the purpose of MCP integration

Silent failure: No error messages make debugging extremely difficult

Additional Context

The configuration format matches the expected schema for

claude-code.mcpServers

Built-in MCP tools (mcp__ide__*) work correctly
This issue persists across multiple VS Code restarts
The problem appears to be specific to external/custom MCP servers

Suggested Investigation

Check if Claude Code is attempting to spawn the MCP server process
Verify if there's additional configuration or setup required for external

MCP servers

Add logging/error messages when MCP servers fail to load
Confirm if external MCP servers are fully supported in Claude Code v2.0.49

Logs Available

VS Code logs location: ~/.config/Code/logs/20251121T163550/

No MCP-related errors found in logs
No indication that Claude Code attempted to load the external server

Error Messages/Logs

2025-11-21 16:35:50.278 [info] CLI main {"_":[],"diff":false,"merge":false,"add":false,"remove":false,"goto":false,"new-window":false,"reuse-window":false,"wait":false,"help":false,"list-extensions":true,"show-versions":true,"pre-release":false,"update-extensions":false,"version":false,"verbose":false,"status":false,"prof-startup":false,"no-cached-data":false,"prof-v8-extensions":false,"disable-extensions":false,"disable-lcd-text":false,"disable-gpu":false,"disable-chromium-sandbox":false,"sandbox":false,"telemetry":false,"debugRenderer":false,"enable-smoke-test-driver":false,"logExtensionHostCommunication":false,"skip-release-notes":false,"skip-welcome":false,"disable-telemetry":false,"disable-updates":false,"transient":false,"use-inmemory-secretstorage":false,"disable-workspace-trust":false,"disable-crash-reporter":false,"skip-add-to-recently-opened":false,"open-url":false,"file-write":false,"file-chmod":false,"force":false,"do-not-sync":false,"do-not-include-pack-dependencies":false,"trace":false,"trace-memory-infra":false,"preserve-env":false,"force-user-env":false,"force-disable-user-env":false,"open-devtools":false,"disable-gpu-sandbox":false,"__enable-file-policy":false,"enable-coi":false,"enable-rdp-display-tracking":false,"disable-layout-restore":false,"disable-experiments":false,"no-proxy-server":false,"no-sandbox":false,"nolazy":false,"force-renderer-accessibility":false,"ignore-certificate-errors":false,"allow-insecure-localhost":false,"disable-dev-shm-usage":false,"profile-temp":false,"logsPath":"/home/jean-louis/.config/Code/logs/20251121T163550"}

Steps to Reproduce

Add custom MCP server configuration to VS Code settings.json
Restart VS Code completely (tested 3+ times)
Open Claude Code
Check available tools - only built-in IDE tools are present

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Code v2.0.49

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Warp

Additional Information