Model Recommendations
After extensive testing across workflows, here are the current go-to models for each use case as of May 2026. RepoPrompt includes an automatic model recommendation system that suggests optimal models based on your current workflow.
GPT-5.5 Update: GPT-5.5 Low is our default for Explore and Context Builder/discovery via Codex CLI. GPT-5.5 Medium is now the default for Engineer/everyday implementation, while GPT-5.5 High remains the in-app choice for heavier planning, review, and pair sessions. Use GPT-5.5 Pro for ChatGPT Pro planning and exports. GPT-5.5 is not available as an OpenAI API or OpenRouter model.
Best Models by Use Case
| Use Case | Model | Access |
|---|---|---|
| Best Agent | GPT-5.5 Medium | Codex CLI |
| Best Planning Model | GPT-5.5 Pro | ChatGPT Pro (web only) |
| Best In-App Planning/Review | GPT-5.5 High | Codex CLI |
| Best Context Builder | GPT-5.5 Low | Codex CLI |
Why These Models?
GPT-5.5 Low for Explore, Medium for Implementation
GPT-5.5 Low (available through Codex CLI) remains our top recommendation for explore and discovery work. GPT-5.5 Medium is the default for engineer agents and general implementation:
- Low keeps repeated codebase exploration and context building fast and efficient
- Medium adds reasoning headroom for everyday multi-step implementation
- Both remain more conversational and easier to steer than prior generations
- Use Medium as the default for most engineer implementation work
Claude Opus 4.6 is still useful as an optional secondary tool for editing-heavy tasks, but it is no longer something we think you need to keep on a separate $100 Max plan.
Codex-only: GPT-5.5 is currently accessible only through Codex CLI. Do not try to configure it as an OpenAI API or OpenRouter model — those endpoints still serve the GPT-5.4 family.
GPT-5.5 Pro for Architectural Planning
GPT-5.5 Pro on ChatGPT Pro is our top planning recommendation because:
- Extended reasoning time produces thorough architectural analysis
- It handles large codebase planning extremely well
- It produces clearer architectural specs and follow-up plans
- It remains the best fit for high-value planning sessions
GPT-5.5 Pro is available only through the ChatGPT Pro web interface — use RepoPrompt's ChatGPT Export copy preset to hand it a curated prompt. It is not a Codex CLI or OpenAI API model.
GPT-5.5 High for In-App Planning/Review
For in-app Chat planning and code review, we recommend Codex CLI with GPT-5.5 High:
- Strong reasoning without the wait times of ChatGPT Pro sessions
- Won't exhaust usage limits as quickly as Pro-style planning sessions
- XHigh is available for the hardest in-app problems
- High is the practical default for most RepoPrompt in-app sessions
GPT-5.5 Low for Context Building
We recommend GPT-5.5 Low as the Context Builder and discovery default. It is the practical Codex CLI default for repeated exploration, file selection, and handoff preparation.
The Context Builder agent benefits from:
- Strong codebase understanding
- Efficient file exploration and selection
- Uses usage limits more slowly than GPT-5.5 Medium/High while staying on the current GPT-5.5 family
- Stays practical for repeated discovery runs while matching the current default recommendation
Recommended Subscriptions
Core Setup (Recommended)
| Plan | Historical price | Use |
|---|---|---|
| ChatGPT Pro | $200/month | Codex CLI (GPT-5.5 Low for explore/discovery, GPT-5.5 Medium for engineer implementation, GPT-5.5 High for heavier work) + GPT-5.5 Pro for planning |
This setup gives you:
- Best-in-class explore/discovery with GPT-5.5 Low and engineer implementation with GPT-5.5 Medium via Codex CLI
- Best-in-class in-app planning/review with GPT-5.5 High via Codex CLI
- Best-in-class architectural planning with GPT-5.5 Pro on ChatGPT Pro web
- No need to add a separate premium Claude plan just to round out the workflow
Optional Claude Add-On
| Plan | Historical price | Use |
|---|---|---|
| Claude Pro | $20/month | Claude Code for light UI work, polish, and fast fixes when you want it |
If you still like Claude's editing style, we now recommend keeping it lightweight: Claude Pro is enough for light UI work and quick fixes. Upgrade beyond that only if Claude Code is a daily driver for you.
Budget Setup (Great Results)
| Plan | Historical price | Use |
|---|---|---|
| ChatGPT Plus | $20/month | Codex CLI + GPT-5.5 Low / GPT-5.5 Medium / GPT-5.5 High |
| Total | $20/month | Context Builder + solid in-app chat |
This gives you:
- Context Builder/explore with GPT-5.5 Low and default implementation with GPT-5.5 Medium
- Strong in-app planning and review with GPT-5.5 High via Codex CLI for heavier sessions
- Excellent results for most tasks without stacking subscriptions
That split is intentional: use GPT-5.5 Low for repeated context-building and explore work, GPT-5.5 Medium for engineer/default implementation, and save GPT-5.5 High for heavier planning/review or pair-agent sessions.
Keep Evolving: Model recommendations change as new releases come out. Check back regularly or follow @repoprompt on X for the latest recommendations.