Cross-check coding agent answers with a second agent
The poster built a tool that automatically sends Claude Code responses to Codex for a second opinion, replacing manual copy-pasting.
Done withClaude CodeCodex
- What they did
- The poster had been manually pasting Claude Code’s replies into Codex for a second opinion, then built Sage to automate that workflow. Sage runs in a separate terminal, watches the main coding agent in real time, and sends each response to another model for review while keeping its own persistent thread; unlike the MCP approach they tried, it can read the codebase, use tools, search the web, and the human chooses whether to apply or ignore the feedback.
- How it went
- They say this workflow led to far fewer bugs and caught bad plans early, but they gave no hard metrics. In comments, users reported it already made useful catches, while the poster noted some rough edges around plan mode and needing to restart after Claude’s /clear.
- Worth knowing
- You can authenticate through a ChatGPT Pro Codex subscription or an API key, but /clear creates a new conversation log, so you have to rerun Sage and pick the new convo.
Try it yourself with Claude Code
Build me a small tool that takes each response Claude Code gives in my project at [repo path] and automatically sends it, with the relevant question and code context, to Codex for a second opinion. It should show me both answers side by side and highlight where they disagree. You're done when I can run one command and see the cross-check for a sample question, and tell me before installing anything or running commands that change my repo.
Want help getting this working? Join the Vibe Coding Academy ↗ Run by Alex Finn, who also runs this site.
Source: Reddit · Undated
Related use cases
Turn tickets into merged pull requests
Pulls tasks from GitHub Issues or Linear, then runs Claude Code or Codex in isolated Kubernetes pods to carry each one through to a PR.
Migrate toolchain, architecture and site design with Claude Code
A developer had Claude Code switch a monorepo to oxlint/oxfmt, restructure the architecture and redesign a site, validating in a loop; the redesign took days instead of weeks.
Produce a finished music release from one chat
Claude Code wrote lyrics, generated and mastered the song, made cover art and a 10-second video via an MCP connector in about 6 minutes; clip joined with ffmpeg outside.
Submitted by Aetherwave Studio
Build a C compiler with a team of parallel agents
Anthropic's engineering write-up on tasking Opus 4.6 agent teams with building a C compiler.
Click through apps to verify its own work
With computer use, Devin built and played a desktop game, ordered on Amazon, and tested its own work by clicking through the app.
Auto-generate a searchable help video library for an app
Used Replit Agent to build a /help page that generates tutorial videos via scenes, Playwright recording, TTS narration and ffmpeg stitching.
Get 5 like this every morning
The best things people got an AI agent to do, each with the prompt to try it.