| name | codex |
| description | Use when the user asks to run Codex CLI (codex exec, codex resume) or references OpenAI Codex for code analysis, refactoring, or automated editing |
Codex Skill Guide
Running a Task
- Ask the user (via
AskUserQuestion) which model to run:gpt-5orgpt-5-codex. - Ask the user (via
AskUserQuestion) which reasoning effort to use:low,medium, orhigh. - Select the sandbox mode required for the task; default to
--sandbox read-onlyunless edits or network access are necessary. - Assemble the command with the appropriate options:
-m, --model <MODEL>--config model_reasoning_effort="<low|medium|high>"--sandbox <read-only|workspace-write|danger-full-access>--full-auto-C, --cd <DIR>--skip-git-repo-check
- When continuing a previous session, use
codex exec resume --lastvia stdin. IMPORTANT: When resuming, you CANNOT specify model, reasoning effort, or other flagsāthe session retains all settings from the original run. Resume syntax:echo "your prompt here" | codex exec resume --last - Run the command, capture stdout/stderr, and summarize the outcome for the user.
Quick Reference
| Use case | Sandbox mode | Key flags |
|---|---|---|
| Read-only review or analysis | read-only |
--sandbox read-only |
| Apply local edits | workspace-write |
--sandbox workspace-write --full-auto |
| Permit network or broad access | danger-full-access |
--sandbox danger-full-access --full-auto |
| Resume recent session | Inherited from original | echo "prompt" | codex exec resume --last (no flags allowed) |
| Run from another directory | Match task needs | -C <DIR> plus other flags |
Following Up
- After every
codexcommand, immediately useAskUserQuestionto confirm next steps, collect clarifications, or decide whether to resume withcodex exec resume --last. - When resuming, pipe the new prompt via stdin:
echo "new prompt" | codex exec resume --last. The resumed session automatically uses the same model, reasoning effort, and sandbox mode from the original session. - Restate the chosen model, reasoning effort, and sandbox mode when proposing follow-up actions.
Error Handling
- Stop and report failures whenever
codex --versionor acodex execcommand exits non-zero; request direction before retrying. - Before you use high-impact flags (
--full-auto,--sandbox danger-full-access,--skip-git-repo-check) ask the user for permission using AskUserQuestion unless it was already given. - When output includes warnings or partial results, summarize them and ask how to adjust using
AskUserQuestion.