Agent skill

codex-cli

Run OpenAI Codex CLI for coding tasks and second-opinion audits. Use when a user asks to run/ask/use Codex, says "codex prompt", or wants Claude to delegate a logic/code review to OpenAI models.

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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/codex-cli-georgekhananaev-claude-skills-vault

SKILL.md

Codex CLI

Run OpenAI Codex CLI locally for second-opinion audits, code review, and non-interactive task execution.

Prerequisites

Codex CLI must be installed and authenticated:

  1. Install: npm install -g @openai/codex
  2. Auth: codex login
  3. Verify: codex --version

Core Execution Pattern

Use codex exec for delegated prompts (non-interactive):

bash
codex exec "Your prompt here"

When the user says "codex prompt", treat it as:

bash
codex exec "<user prompt>"

Model Guidance

Use the default configured model unless the user asks otherwise.

Latest tested working model in this environment:

bash
codex exec -m gpt-5.3-codex "Your prompt"

Compatibility note:

  • gpt-5-codex may fail if config uses model_reasoning_effort = "xhigh".
  • If you must use gpt-5-codex, set reasoning effort explicitly:
bash
codex exec -m gpt-5-codex -c model_reasoning_effort="high" "Your prompt"

Commands

Non-Interactive Execution

bash
# Basic task
codex exec "Audit this logic for edge cases"

# Explicit model
codex exec -m gpt-5.3-codex "Review this implementation strategy"

# Full-auto mode (sandboxed, lower friction)
codex exec --full-auto "Implement the requested refactor"

# Read-only sandbox (analysis only)
codex exec -s read-only "Find bugs in this code path"

# Workspace-write sandbox
codex exec -s workspace-write "Apply the fix and update tests"

# Custom working directory
codex exec -C /path/to/project "Evaluate this repository"

# Save final output to file
codex exec -o output.txt "Summarize key risks"

# JSONL event stream
codex exec --json "Produce structured findings"

# Pipe context from stdin
cat context.txt | codex exec -

Code Review

Use codex review for repository diffs:

bash
# Review uncommitted changes
codex review --uncommitted

# Review against a base branch
codex review --base main

# Review a specific commit
codex review --commit abc123

# Custom review instructions
codex review "Focus on security issues"

# Combined
codex review --base main "Check for performance regressions"

Important Flag Placement

--search and -a/--ask-for-approval are top-level flags. Put them before exec or review.

Correct:

bash
codex --search -a on-request exec "Your prompt"
codex --search -a on-request review --uncommitted

Avoid:

bash
codex exec --search "Your prompt"
codex exec -a on-request "Your prompt"

Useful Flags

Flag Description
-m Model (recommended explicit example: gpt-5.3-codex)
-s Sandbox: read-only, workspace-write, danger-full-access
-a Approval policy (untrusted, on-failure, on-request, never) as a top-level flag
-C Working directory
-o Write last message to file
--full-auto Sandboxed auto-execution (-a on-request -s workspace-write)
--json JSONL event output
--search Enable web search tool as a top-level flag
--add-dir Additional writable directories
-c key=value Override config (example: -c model_reasoning_effort="high")

Best Practices

  • Prefer codex exec for delegated prompts instead of interactive codex
  • Start with -s read-only for audits and second opinions
  • Use --full-auto only when you expect autonomous edits
  • Keep prompts explicit about expected output format
  • Add -o when another tool or agent must consume the result
  • Run codex review --uncommitted before committing as a quick extra pass

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