Mcp support issue

Resolved 💬 6 comments Opened Sep 27, 2025 by zuopanA Closed Nov 12, 2025

💡 Likely answer: A maintainer (cpjet64, contributor) responded on this thread — see the highlighted reply below.

What version of Codex is running?

v0.41.0

Which model were you using?

_No response_

What platform is your computer?

_No response_

What steps can reproduce the bug?

I'm using a Windows 10 system. When configuring MCP, it fails with the following configuration:
[mcp_servers.context7]
command = "npx"
args = ["-y", "@upstash/context7-mcp"]

But it succeeds with this configuration:
[mcp_servers.context7]
command = "D:\\Program Files\\nodejs\\npx.cmd"
args = ["-y", "@upstash/context7-mcp"]
env = { SYSTEMROOT = 'C:\Windows',"PROGRAMFILES(X86)" = 'C:\Program Files (x86)' }

Is there a way to simplify the MCP configuration?

What is the expected behavior?

_No response_

What do you see instead?

_No response_

Additional information

_No response_

View original on GitHub ↗

6 Comments

synestiqx · 11 months ago

It exists — you just need to add which before the command to get the full path.
Windows requires the full path.

cpjet64 contributor · 11 months ago

There are already multiple PRs in about the PATH/PATHEX issues. Once they get implemented these issues will be a thing of the past. If you have other issues you can look at https://github.com/openai/codex/issues/4180#issuecomment-3332020165 for the full env details that are available.

waldoalvarez00 · 11 months ago

With v0.42.0 my MCP started to not work anymore. Did not changed configuration at all. Fails with timeout. I am using Laravel boost MCP. It was working fine with v0.41.0 therefore seems it broke. I am thinking to go back to 41 until this bug gets resolved.

cpjet64 contributor · 11 months ago

@waldoalvarez00 what OS are you on? share your config and maybe me or someone else can help you get it working again.

synestiqx · 11 months ago

@waldoalvarez00

Exactly, that's another problem :)
Now you can set the waiting time for MCP in the configuration.

Although I'm not sure how much it will help, it should work.
You can try starting MCP manually in a separate terminal first, just to test.

Basically, it's a synchronization issue — MCP doesn’t have enough time to start up.
In the MCP section of the README, there should be instructions on how to set the timeout for MCP in the config.

I think about two months ago, I submitted a PR that solved both issues :)
I got a response saying there was some concern about how reactive loading of MCP might affect the model’s performance.
However, I believe this could have been fixed by now :)

waldoalvarez00 · 10 months ago

@waldoalvarez00 Exactly, that's another problem :) Now you can set the waiting time for MCP in the configuration. Although I'm not sure how much it will help, it should work. You can try starting MCP manually in a separate terminal first, just to test. Basically, it's a synchronization issue — MCP doesn’t have enough time to start up. In the MCP section of the README, there should be instructions on how to set the timeout for MCP in the config. I think about two months ago, I submitted a PR that solved both issues :) I got a response saying there was some concern about how reactive loading of MCP might affect the model’s performance. However, I believe this could have been fixed by now :)

Thanks. I managed to solve it by setting higher times in configuration. Being working ok after setting that. After several updates kept working ok.