Previously, the model couldn't see why MCP tool calls failed, many of which were the model using the parameters incorrectly. A common failure is the model stringifying the json for the notion-update-page tool which it then couldn't correct. I want to do some system prompt massaging around this as well. However, it is crucial that the model sees the error so it can fix it. Before: <img width="2984" height="832" alt="CleanShot 2025-10-17 at 13 02 36" src="https://github.com/user-attachments/assets/709a3d27-b71b-4d8d-87b6-9b2d7fe4e6f2" /> After: <img width="2488" height="1550" alt="CleanShot 2025-10-17 at 13 01 18" src="https://github.com/user-attachments/assets/13a0b7dc-fdad-4996-bf2d-0772872c34fc" /> 🎉 <img width="1078" height="568" alt="CleanShot 2025-10-17 at 13 09 30" src="https://github.com/user-attachments/assets/64cde8be-9e6c-4e61-b971-c2ba22504292" /> Fixes #4707
codex-core
This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.
Dependencies
Note that codex-core makes some assumptions about certain helper utilities being available in the environment. Currently, this
macOS
Expects /usr/bin/sandbox-exec to be present.
Linux
Expects the binary containing codex-core to run the equivalent of codex sandbox linux (legacy alias: codex debug landlock) when arg0 is codex-linux-sandbox. See the codex-arg0 crate for details.
All Platforms
Expects the binary containing codex-core to simulate the virtual apply_patch CLI when arg1 is --codex-run-as-apply-patch. See the codex-arg0 crate for details.