Codex desktop exits the tool call immediately when any MCP tool is invoked

What version of the Codex App are you using (From “About Codex” dialog)?

26.426.12240

What subscription do you have?

Third-party provider (aihubmix)

What platform is your computer?

Darwin 25.0.0 arm64 arm

What issue are you seeing?

In Codex desktop, MCP tools are unusable. As soon as an MCP tool is invoked, the tool call ends immediately instead of running normally. This makes MCP-based workflows impossible to use. Non-MCP behavior appears normal, but every MCP invocation fails in the same way.

What steps can reproduce the bug?

Open Codex desktop.
Start a normal conversation in a workspace.
Ask the agent to use any MCP tool.
The moment the MCP tool is invoked, the tool call ends immediately.
This happens consistently across repeated attempts.

<img width="850" height="201" alt="Image" src="https://github.com/user-attachments/assets/5f4b1fbf-fc1a-4b73-aea2-5ec33226a060" />

What is the expected behavior?

_No response_

Additional information

_No response_