codex

name	codex
description	Deploy OpenAI Codex CLI agents to implement tasks autonomously. Use when the user asks to run codex, deploy an agent, or delegate implementation work. Use when this capability is needed.
metadata	{"author":"evmts"}

Codex CLI Agent Deployment

Use the OpenAI Codex CLI to deploy autonomous coding agents. Codex agents read files, explore the codebase, and write code independently.

Quick Reference

Non-interactive mode (for background/parallel tasks):

codex exec -c model_reasoning_effort="xhigh" --dangerously-bypass-approvals-and-sandbox "<prompt>"

Interactive mode (requires a TTY — cannot run from background tasks):

codex -c model_reasoning_effort="xhigh" --yolo "<prompt>"

IMPORTANT: Interactive mode (codex without exec) requires a TTY. When running from Claude Code's Bash tool with run_in_background: true, you MUST use codex exec instead. The interactive TUI will fail with "stdin is not a terminal" in background mode.

Key Flags

Flag	Purpose
exec	Non-interactive subcommand (required for background execution)
-c model_reasoning_effort="xhigh"	Maximum reasoning effort
-c model="<model>"	Override model (default: gpt-5.2-codex)
--dangerously-bypass-approvals-and-sandbox	Skip all prompts, no sandbox (use for trusted repos)
--full-auto	Sandboxed auto-execution (safer alternative to bypass)
--yolo	Interactive mode equivalent of bypass (TTY only)
-C <dir>	Set working directory
-i <file>	Attach image(s) to the prompt
--search	Enable web search tool
-s <mode>	Sandbox: read-only, workspace-write, danger-full-access
-o <file>	Write last agent message to file
--json	Output JSONL events to stdout

Deployment Patterns

Single background agent

codex exec -c model_reasoning_effort="xhigh" --dangerously-bypass-approvals-and-sandbox "Read issues/008-image-paste-in-chat.md and implement it. Read all relevant files before making changes."

Run with run_in_background: true in the Bash tool, then check output with TaskOutput.

Multiple parallel agents

Launch several codex exec commands simultaneously using parallel Bash tool calls, each with run_in_background: true. Each gets its own task ID for monitoring.

Resume a session

codex exec resume --last   # Resume most recent
codex resume               # Interactive picker (TTY only)

Code review

codex exec review          # Review current changes
codex review               # Interactive review (TTY only)

Prompt Best Practices

1. Always tell codex to read the relevant files first: "Read X.swift and Y.swift, then implement..."
2. Reference issue files by path: "Read issues/008-image-paste-in-chat.md carefully, then..."
3. Be specific about scope: List exact requirements rather than vague instructions
4. Mention the architecture: "This is a SwiftUI app using STTextView for editing..."

Monitoring Background Agents

After launching with run_in_background: true:

• Use TaskOutput with block: false to check status without waiting
• Use TaskOutput with block: true to wait for completion
• Read the output file path directly with the Read tool for full logs

Other Subcommands

Command	Purpose
codex apply / codex a	Apply the latest diff from a codex session as git apply
codex cloud	Browse Codex Cloud tasks
codex fork	Fork a previous session
codex debug	Debugging tools
codex mcp	Run as MCP server

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