[Bug]: MCP client for `XcodeBuildMCP` failed to start: MCP startup failed

[rursache]

Bug Description

Adding

[mcp_servers.XcodeBuildMCP]
command = "npx"
args = ["-y", "xcodebuildmcp@beta"]

[mcp_servers.XcodeBuildMCP.env]
INCREMENTAL_BUILDS_ENABLED = "false"
XCODEBUILDMCP_SENTRY_DISABLED = "true"

to ~/.codex/config.toml

will make codex throw warning at startup:

⚠ MCP client for `XcodeBuildMCP` failed to start: MCP startup failed: handshaking with MCP
  server failed: connection closed: initialize response

⚠ MCP startup incomplete (failed: XcodeBuildMCP)

Debug Output

XcodeBuildMCP Doctor

Generated: 2026-02-09T11:50:20.998Z
Server Version: 2.0.0-beta.1

## System Information
- platform: darwin
- release: 25.2.0
- arch: arm64
- cpus: 14 x Apple M4 Pro
- memory: 48 GB
- hostname: Radus-Mac-Mini-M4.local
- username: radu
- homedir: /Users/radu
- tmpdir: /var/folders/87/hj7rnyln3h36m5yj9mdg6v100000gn/T

## Node.js Information
- version: v25.6.0
- execPath: /opt/homebrew/Cellar/node/25.6.0/bin/node
- pid: 31132
- ppid: 30435
- platform: darwin
- arch: arm64
- cwd: /Users/radu/Downloads
- argv: /opt/homebrew/Cellar/node/25.6.0/bin/node /opt/homebrew/bin/XcodeBuildMCP doctor doctor

## Xcode Information
- version: Xcode 26.3 - Build version 17C519
- path: /Applications/Xcode.app/Contents/Developer
- selectedXcode: /Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild
- xcrunVersion: xcrun version 72.

## Dependencies
- axe: ✅ v1.3.0
- xcodemake: ❌ Not found
- mise: ❌ Not found

## Environment Variables
- INCREMENTAL_BUILDS_ENABLED: (not set)
- DEVELOPER_DIR: (not set)
- HOME: /Users/radu
- USER: radu
- TMPDIR: /var/folders/87/hj7rnyln3h36m5yj9mdg6v100000gn/T/
- NODE_ENV: (not set)
- SENTRY_DISABLED: (not set)
- XCODEBUILDMCP_RUNTIME: cli
- XCODEBUILDMCP_SILENCE_LOGS: true

PATH

/opt/homebrew/opt/openjdk/bin
/Users/radu/.bun/bin
/Users/radu/Library/pnpm
/Users/radu/.antigravity/antigravity/bin
/Users/radu/.rbenv/shims
/Users/radu/.rbenv/bin
/Users/radu/.local/bin
/opt/homebrew/opt/python@3.14/libexec/bin
/opt/homebrew/bin
/opt/homebrew/sbin
/usr/local/bin
/System/Cryptexes/App/usr/bin
/usr/bin
/bin
/usr/sbin
/sbin
/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin
/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin
/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin
/opt/pmk/env/global/bin
//Applications/Topaz Photo.app/Contents/Resources/bin
/Library/Apple/usr/bin
/Applications/VMware Fusion.app/Contents/Public
/usr/local/share/dotnet
/Applications/iTerm.app/Contents/Resources/utilities
/Users/radu/.orbstack/bin
/Users/radu/.lmstudio/bin

Feature Status

UI Automation (axe)

• Available: ✅ Yes
• UI Automation Supported: ✅ Yes

Incremental Builds

• Enabled: ❌ No
• Available: ❌ No
• Makefile exists: ❌ No

Mise Integration

• Running under mise: ❌ No
• Mise available: ❌ No

Debugger Backend (DAP)

• lldb-dap available: ✅ Yes
• Selected backend: dap

Available Tools

• Total Plugins: 94
• Plugin Directories: 14
• debugging: 8 tools
• device: 14 tools
• doctor: 1 tools
• logging: 4 tools
• macos: 11 tools
• project-discovery: 5 tools
• project-scaffolding: 2 tools
• session-management: 3 tools
• simulator: 19 tools
• simulator-management: 8 tools
• swift-package: 6 tools
• ui-automation: 11 tools
• utilities: 1 tools
• workflow-discovery: 1 tools

Runtime Tool Registration

• Enabled Workflows: 0
• Registered Tools: 0
• Note: Runtime registry unavailable.

Tool Availability Summary

• Build Tools: ✅ Available
• UI Automation Tools: ✅ Available
• Incremental Build Support: ❌ Not available

Sentry

• Sentry enabled: ✅ Yes

Troubleshooting Tips

• If UI automation tools are not available, install axe: brew tap cameroncooke/axe && brew install axe
• If incremental build support is not available, you can download the tool from https://github.com/cameroncooke/xcodemake. Make sure it's executable and available in your PATH
• To enable xcodemake, set environment variable: export INCREMENTAL_BUILDS_ENABLED=1
• For mise integration, follow instructions in the README.md file

### Editor/Client

Codex v0.98.0

### MCP Server Version

latest / beta

### LLM

gpt-5.3-codex high

[coderabbitai]

🔗 Related PRs

#200 - Add MCP setup instructions for Xcode's integrated Claude Code and Codex agents [merged]

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[lucasmariani]

@rursache I ran into the same issue. I fixed it by updating to the latest 2.0.0 version.

in your config.toml, replace
args = ["-y", "xcodebuildmcp@beta"]
with
args = ["-y", "xcodebuildmcp@2.0.0", "mcp"]

[rursache]

@lucasmariani thanks, running npm install -g xcodebuildmcp@latest and using the latest tag in the mcp config also fixed it (verified im still running 2.0.0 with xcodebuildmcp -v)

[cameroncooke]

Thanks for the report. Yes the latest version requires configuration updates see: https://x.com/camsoft2000/status/2020816255641321687?s=46