New featureModels ·
GPT-5.3 Codex and Gemini 3.1 Pro Preview
GPT-5.3 CodexGemini 3.1 Pro Preview
What it does
Two models joined the allowlist: OpenAI's Codex variant and Google's Gemini 3.1 Pro Preview.
Why it matters
Codex for agents that read or write code; Gemini 3.1 Pro for long-context work over big document sets.
The specs
- GPT-5.3 Codex
- 1,000,000-token context, 128,000-token output, text and images, Actions and reasoning (Fast to Smartest). Every plan.
- Gemini 3.1 Pro Preview
- 1,048,576-token context, 65,536-token output, text and images, Actions and reasoning. Gold and Pro.
Codex is trained on code, which shows less in whether it can write a function and more in how it handles structured output — JSON, config, and anything with a schema an agent has to hit exactly.