Codex Sub-Agent Behavior Sparks Debate

zeeg · x · 2026-07-12

The discussion revolves around model performance differences in the Codex environment. Some argue that if a model needs subsequent updates to improve, it indicates shortcomings beyond standard benchmarks. Others remind users to check the model's corresponding system prompt in a custom harness, as Codex's prompt might differ from external testing setups.

Responses also note that Codex's system prompt is highly streamlined and requires user consent by default to call sub-agents outside ultra mode. If explicitly prompted to use sub-agents heavily, it will do so, but at a corresponding cost.

Related event: Codex Sub-Agent Differences Traced to Training and System Prompts(3 posts)→

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