Key Takeaways
Gemini 3.1 Pro Preview Custom Tools wins:
- Larger context window
GPT-5 Codex wins:
- Cheaper input tokens
- Cheaper output tokens
- Faster response time
- Higher intelligence benchmark
- Better at coding
- Better at math
Price Advantage
GPT-5 Codex
Benchmark Advantage
GPT-5 Codex
Context Window
Gemini 3.1 Pro Preview Custom Tools
Speed
GPT-5 Codex
Pricing Comparison
Benchmark Comparison
Context & Performance
Capabilities
Feature Comparison
| Feature | Gemini 3.1 Pro Preview Custom Tools | GPT-5 Codex |
|---|---|---|
Vision (Image Input) | ||
Tool/Function Calls | ||
Reasoning Mode | ||
Audio Input | ||
Audio Output | ||
PDF Input | ||
Prompt Caching | ||
Web Search |
License & Release
| Property | Gemini 3.1 Pro Preview Custom Tools | GPT-5 Codex |
|---|---|---|
| License | Proprietary | Proprietary |
| Author | OpenAI | |
| Released | Feb 2026 | Sep 2025 |
Gemini 3.1 Pro Preview Custom Tools Modalities
Input
textaudioimagevideofile
Output
text
GPT-5 Codex Modalities
Input
textimage
Output
text