Codex
Models, options, and features for Codex.
Send a codex block to run a session with Codex:
JSON
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{
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"codex": {
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"prompt": "Find and fix the failing test.",
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"model": "gpt-6-sol",
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"effort": "medium"
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}
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}
In agent YAML, the same fields go under session.codex. The CLI picks the harness from --model:
Shell
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el --model gpt-6-astra -e cloud_agent_environment "Find and fix the failing test."
Options
The task.
gpt-6-astra, gpt-6-sol, gpt-6-luna, or gpt-5.6-sol.
Reasoning effort. GPT-6 Astra doesn't accept none.
Features
| Feature | Support |
|---|---|
| Follow-up messages | All models |
| MCP servers | All models |
| JSON output | All models |
| Skills | All models |
| Images in messages | All models |
Subscription
To pay with your ChatGPT plan instead of credits, connect your Codex subscription. Ellipsis refreshes the login when needed.