MCP client for `unityMCP` failed to start: request timed out - Codex

[petaaar88]

When using the Codex CLI or the Codex IDE extension for VS Code, I get the message:
"MCP client for unityMCP failed to start: request timed out."
I tried using other AI tools like Claude Desktop and GitHub Copilot, and they worked correctly.
I configured the config.toml file as described in the documentation. Also Codex works well with other MCP servers.

[Scriptwonder]

Will check in later. Thank you for letting us know!

[Scriptwonder]

@petaaar88 are you using Codex CLI on Windows? This seems to be an existing issue for servers not being able to start on Windows machines: openai/codex#4180.

I tried the solution mentioned in that Issue, and it works on my end with the following toml file, but you will need another shell to keep the uv command running, since, for some reason, Codex does not fully support Windows PowerShell commands at this point. Let me know if this works!

[mcp_servers.unityMCP]
command = "uv"
args = ["run", "--directory", "C:\Users\scriptwonder\AppData\Local\UnityMCP\UnityMcpServer\src", "server.py"]
startup_timeout_sec = 30

//Replace YOURUSERPROFILEGOESHERE with your profile name
[mcp_servers.unityMCP.env]
SystemRoot="C:\Windows"
APPDATA = "C:\Users\YOURUSERPROFILEGOESHERE\AppData\Roaming"
COMSPEC = "C:\Windows\System32\cmd.exe"
HOMEDRIVE = "C:"
HOMEPATH = "\Users\YOURUSERPROFILEGOESHERE"
LOCALAPPDATA = "C:\Users\YOURUSERPROFILEGOESHERE\AppData\Local"
POWERSHELL = "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe"
PROGRAMDATA = "C:\ProgramData"
PROGRAMFILES = "C:\Program Files"
PWSH = "C:\Program Files\PowerShell\7\pwsh.exe"
SYSTEMDRIVE = "C:"
SYSTEMROOT = "C:\Windows"
TEMP = "C:\Users\YOURUSERPROFILEGOESHERE\AppData\Local\Temp"
TMP = "C:\Users\YOURUSERPROFILEGOESHERE\AppData\Local\Temp"
USERPROFILE = "C:\Users\YOURUSERPROFILEGOESHERE"

[msanatan]

@petaaar88 are you using Codex CLI on Windows? This seems to be an existing issue for servers not being able to start on Windows machines: openai/codex#4180.

I tried the solution mentioned in that Issue, and it works on my end with the following toml file, but you will need another shell to keep the uv command running, since, for some reason, Codex does not fully support Windows PowerShell commands at this point. Let me know if this works!

[mcp_servers.unityMCP] command = "uv" args = ["run", "--directory", "C:\Users\scriptwonder\AppData\Local\UnityMCP\UnityMcpServer\src", "server.py"] startup_timeout_sec = 30

//Replace YOURUSERPROFILEGOESHERE with your profile name [mcp_servers.unityMCP.env] SystemRoot="C:\Windows" APPDATA = "C:\Users\YOURUSERPROFILEGOESHERE\AppData\Roaming" COMSPEC = "C:\Windows\System32\cmd.exe" HOMEDRIVE = "C:" HOMEPATH = "\Users\YOURUSERPROFILEGOESHERE" LOCALAPPDATA = "C:\Users\YOURUSERPROFILEGOESHERE\AppData\Local" POWERSHELL = "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe" PROGRAMDATA = "C:\ProgramData" PROGRAMFILES = "C:\Program Files" PWSH = "C:\Program Files\PowerShell\7\pwsh.exe" SYSTEMDRIVE = "C:" SYSTEMROOT = "C:\Windows" TEMP = "C:\Users\YOURUSERPROFILEGOESHERE\AppData\Local\Temp" TMP = "C:\Users\YOURUSERPROFILEGOESHERE\AppData\Local\Temp" USERPROFILE = "C:\Users\YOURUSERPROFILEGOESHERE"

Excellent work @Scriptwonder ! I'll put it in the next Discord announcement, and probably update the README

[BlindsidedGames]

I managed to get it working by configuring to codexCLI and then going into the config.toml and adding

env = { SystemRoot="C:\Windows" }

#311 (comment)

[msanatan]

I managed to get it working by configuring to codexCLI and then going into the config.toml and adding

env = { SystemRoot="C:\Windows" }

[#311 (comment)](https://github.com//issues/311#issuecomment-3419130158)

Can someone else test this? Not currently by my PC. If it works for others we can quickly adjust the code and help the other users.

Great work @BlindsidedGames

[StuBedore]

I managed to get it working by configuring to codexCLI and then going into the config.toml and adding
env = { SystemRoot="C:\Windows" }

[#311 (comment)](https://github.com/[/issues/311](https://github.com/CoplayDev/unity-mcp/issues/311)#issuecomment-3419130158)

Can someone else test this? Not currently by my PC. If it works for others we can quickly adjust the code and help the other users.

Great work @BlindsidedGames

I had the same problem and @BlindsidedGames suggestion did indeed fix it for me as well.

[BlindsidedGames]

I managed to get it working by configuring to codexCLI and then going into the config.toml and adding
env = { SystemRoot="C:\Windows" }

[#311 (comment)]([https://github.com//issues/311#issuecomment-3419130158](#311))

Can someone else test this? Not currently by my PC. If it works for others we can quickly adjust the code and help the other users.
Great work @BlindsidedGames

I had the same problem and @BlindsidedGames suggestion did indeed fix it for me as well.

Huzzah! I found the solution somewhere else on GitHub relating to some other MCP thing and decided to try it for this. Not sure where the relevant post is to link it though. Glad to have helped here though!

[Scriptwonder]

It is interesting that I tried this at first and it did not work (which leads me to the long implementation)! Wondering whats causing the problem on my end.

[msanatan]

It is interesting that I tried this at first and it did not work (which leads me to the long implementation)! Wondering whats causing the problem on my end.

OS installed in C drive? I'll be able to test and push this change up in a couple of hours

[msanatan]

It is interesting that I tried this at first and it did not work (which leads me to the long implementation)! Wondering whats causing the problem on my end.

It's possible your SystemRoot is another value. Try to print the env var, in either case the code I've added should pick up the environment value and default to "C:\Windows". Should be released tomorrow morning with some other fixes