How do I install the Codex skill?

Run npx skillmds@latest add tomevault-io/codex-13 in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Codex safe to use?

This skill has not completed SkillMD's automated safety review yet. Independent scanners report: SkillSpector: WARNING, Skill Scanner: PASS. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Codex?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Codex free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

tomevault-io (@tomevault-io) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Codex by tomevault-io — Agent Skill

Name: Codex
Author: tomevault-io

File contents

Codex CLI Delegation

Use Codex CLI as a parallel agent with its own context window. Prefer codex exec for headless runs and codex for the TUI.

When to Use

Code review or spec/plan review
Debugging second opinion
Parallel implementation in an isolated worktree

Quickstart

codex exec --sandbox read-only "Review src/auth against SPEC.md. Focus on security and tests."
codex exec --full-auto --cd ../worktrees/task-3 "Implement Task 3 from IMPLEMENTATION_PLAN.md."

Exec Inputs

PROMPT string, or - to read stdin.
--image, -i attaches one or more images to the first message.

Config and Model Overrides

--model, -m overrides the configured model (e.g., gpt-5-codex).
--profile, -p selects a profile from ~/.codex/config.toml.
--config, -c key=value overrides config values (repeatable).
--oss uses the local open source provider (requires Ollama).
--cd, -C sets the working directory before execution.
--skip-git-repo-check allows running outside a Git repo.

Safety Controls

--sandbox, -s: read-only | workspace-write | danger-full-access.
--ask-for-approval, -a: untrusted | on-failure | on-request | never.
--full-auto: sets --ask-for-approval on-request and --sandbox workspace-write.
--dangerously-bypass-approvals-and-sandbox, --yolo: no approvals or sandbox.
--add-dir: grant extra write roots.
--search: enable web search tool usage.

Output and Scripting

--json / --experimental-json: newline-delimited JSON events.
--output-last-message, -o <path>: write final assistant message to a file.
--output-schema <path>: validate the final response against a JSON Schema.
--color <always|never|auto>: control ANSI output.

Session Control

codex resume [SESSION_ID] or codex resume --last [--all].
codex exec resume [SESSION_ID] to continue non-interactive runs.
codex fork [SESSION_ID] to branch a prior interactive session.

Notes

Global flags apply to subcommands; place them after the subcommand (e.g., codex exec --oss ...).
Codex runs with its own context window; include all necessary context in the prompt.

Converted and distributed by TomeVault — claim your Tome and manage your conversions.

---name: codex-13description: This skill should be used when the user asks to "use Codex CLI", "codex exec", "get a Codex second opinion", or "run a Codex review" as a separate agent. Use when this capability is needed.---# Codex CLI DelegationUse Codex CLI as a parallel agent with its own context window. Prefer `codex exec` for headless runs and `codex` for the TUI.## When to Use- Code review or spec/plan review- Debugging second opinion- Parallel implementation in an isolated worktree## Quickstart```bashcodex exec --sandbox read-only "Review src/auth against SPEC.md. Focus on security and tests."codex exec --full-auto --cd ../worktrees/task-3 "Implement Task 3 from IMPLEMENTATION_PLAN.md."```## Exec Inputs- PROMPT string, or `-` to read stdin.- `--image, -i` attaches one or more images to the first message.## Config and Model Overrides- `--model, -m` overrides the configured model (e.g., `gpt-5-codex`).- `--profile, -p` selects a profile from `~/.codex/config.toml`.- `--config, -c key=value` overrides config values (repeatable).- `--oss` uses the local open source provider (requires Ollama).- `--cd, -C` sets the working directory before execution.- `--skip-git-repo-check` allows running outside a Git repo.## Safety Controls- `--sandbox, -s`: `read-only` | `workspace-write` | `danger-full-access`.- `--ask-for-approval, -a`: `untrusted` | `on-failure` | `on-request` | `never`.- `--full-auto`: sets `--ask-for-approval on-request` and `--sandbox workspace-write`.- `--dangerously-bypass-approvals-and-sandbox`, `--yolo`: no approvals or sandbox.- `--add-dir`: grant extra write roots.- `--search`: enable web search tool usage.## Output and Scripting- `--json` / `--experimental-json`: newline-delimited JSON events.- `--output-last-message, -o <path>`: write final assistant message to a file.- `--output-schema <path>`: validate the final response against a JSON Schema.- `--color <always|never|auto>`: control ANSI output.## Session Control- `codex resume [SESSION_ID]` or `codex resume --last [--all]`.- `codex exec resume [SESSION_ID]` to continue non-interactive runs.- `codex fork [SESSION_ID]` to branch a prior interactive session.## Notes- Global flags apply to subcommands; place them after the subcommand (e.g., `codex exec --oss ...`).- Codex runs with its own context window; include all necessary context in the prompt.---> Converted and distributed by [TomeVault](https://tomevault.io/claim/treygoff24) — claim your Tome and manage your conversions.

Frequently asked questions

Codex