What is the Ask Codex skill for Claude Code?

It is a specialized skill that allows Claude to consult OpenAI Codex (GPT-5) as a second opinion for complex investigation, debugging, or code review tasks.

Can Codex modify my project files directly?

No, Codex runs in a strictly read-only sandbox. It analyzes the project and provides recommendations which Claude then evaluates and implements only with your approval.

Is GPT-5 required for this skill to work?

The skill is configured to use the highest available reasoning models like GPT-5 to ensure maximum depth, though it can be adjusted via CLI flags if necessary.

How does Ask Codex handle large codebases?

Instead of dumping entire files, it uses focused prompts with file paths and line references, utilizing Codex's ability to access the project structure efficiently.

How long does a Codex analysis typically take?

Complex reasoning can take between 2 to 5 minutes. The skill runs these tasks in the background so you can continue working while the analysis is processed.

Ask Codex

Name: Ask Codex
Author: umputun

byumputun

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269

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開発者ツール

Consults OpenAI Codex (GPT-5) to provide deep reasoning and a second opinion on complex debugging and code review tasks.

Ask Codex acts as an advanced peer reviewer within Claude Code, allowing Claude to leverage external reasoning models to investigate root causes, validate logic, and provide architectural feedback. By operating in a read-only sandbox with full project context, it ensures that high-level analysis is performed safely, providing Claude with actionable insights to implement. This skill is particularly useful for difficult 'Heisenbugs' or complex refactoring where a second perspective on the codebase can prevent regressions and improve code quality.

主な機能

01269 GitHub stars

02Context-aware prompting using project-level documentation and file references

03Background execution to handle long-running reasoning tasks without blocking

04Deep reasoning via GPT-5 for complex logical investigation

05Read-only sandbox mode ensuring zero accidental modifications during analysis

06Structured output for clear comparison between Codex analysis and Claude's assessment

ユースケース

01Architectural brainstorming where a second model can validate proposed implementation patterns

02Investigating elusive bugs that require deep logical analysis and root cause identification

03Performing a secondary AI code review to ensure best practices and catch edge cases

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add umputun/cc-thingz ask-codex

For use in Claude.ai and ChatGPT