Codex in Claude Code: OpenAI plugin for integration

OpenAI Codex Plugin for Claude Code: Cross-Platform AI Agent Integration

OpenAI has released an open-source plugin that enables direct calls to Codex from Anthropic's Claude Code environment. A developer from the Developer Experience team, Dominic Kundel, created the tool to simplify access to Codex features for Claude Code users. Division head Romain Uy confirmed support for the project. The plugin uses a locally deployed Codex CLI and requires only a ChatGPT subscription or an OpenAI API key.

This solution reflects the trend toward unifying AI agent ecosystems, where tools from competitors become complementary. Previously, Claude Code users had to manually integrate Codex for code reviews and handling complex tasks with GPT-5.4—the plugin automates these scenarios.

Plugin Slash Commands

The plugin introduces a set of specialized commands for interacting with Codex:

• /codex:review — standard code review with analysis of style, security, and performance.
• /codex:adversarial-review — stress-testing architecture, identifying vulnerabilities in edge cases.
• /codex:rescue — asynchronous task delegation to Codex for background execution without blocking the main agent.

These commands integrate into the Claude Code interface as native slash commands, maintaining compatibility with existing skills. Plugin and skill formats in Claude Code and Codex are unified, facilitating such integration.

Technical Implementation Details

The plugin relies on AI agent compatibility protocols similar to ACP for JetBrains IDEs. Codex CLI is installed locally, minimizing latency and ensuring data privacy. Authentication occurs via OpenAI API or ChatGPT session, without sharing code with third parties.

The community already uses similar hacks: catalogs like SkillsMP contain thousands of cross-compatible skills between agents. The plugin standardizes the process, lowering the entry barrier for mid-level and senior developers working with mixed AI tool stacks.

The market for AI agents in devops and codegen is moving toward open standards. Anthropic's lack of response underscores platform neutrality—focus on user experience over competition.

Benefits for Developers

The integration extends Claude Code capabilities without migrating to other tools:

• Hybrid Review: Combines Claude's strengths in contextual analysis with Codex's alternative implementation generation.
• Background Tasks: /codex:rescue offloads the main agent for parallel refactoring or optimization.
• Ecosystem Compatibility: Support for SkillsMP and ACP simplifies skill transfer between platforms.

In community benchmarks, hybrid setups show 20–30% better results in adversarial testing compared to monolithic agents.

Key Points

• The plugin is open-source and uses local Codex CLI for privacy and speed.
• Three key commands: review, adversarial-review, rescue—for the full codegen cycle.
• Requires only OpenAI API or ChatGPT subscription, no extra costs.
• Accelerates cross-platform development in unified AI ecosystems.
• Confirms the trend toward openness: competitors' tools integrate without restrictions.

— Editorial Team