Inside OpenAI Codex

A thread you can test

Tools

3 notes move from the word to a real choice at work — understand it first, then decide whether to use it.

READING THREADOPEN
3notes
HOW TO READStart where you are stuck, then follow the evidence and trade-offs

Each note stands alone, or becomes the next step in this thread.

Inside OpenAI CodexNo login

THE QUESTION THIS PAGE ANSWERS

ANSWER FIRST

What is Tools, and which AI decisions does it change?

Codex plans the tool list per sample: identity trims sources, exposure decides visible vs searchable, then the result freezes into StepContext This page keeps the related concepts, common mistakes, and practical notes in one reading thread.

DECISION RULE

First decide whether you are blocked by a definition, a choice, or verification; then choose the closest of the 3 notes below.

TRY NEXT

Start with “The tool list the model sees is computed for one sample,” then restate the conclusion using your own task.

WATCH FOR

Do not treat every method in a topic as interchangeable. The answer changes with the input, risk, and acceptance bar.

THIS QUESTION THREAD

Put the word back inside the choice it changes.

3 notes
Tools

The tool list the model sees is computed for one sample

Codex plans the tool list per sample: identity trims sources, exposure decides visible vs searchable, then the result freezes into StepContext

Inside OpenAI Codex 9 min →
Tools

Tell the model it can go parallel — a lock keeps the floor

The model is allowed to emit several tool calls at once. A request flag, a per-tool boolean, and one read-write lock work separately; history still books in emit order

Inside OpenAI Codex 11 min →
Execution

One door: a command forks by features

After a command enters the unified exec door, it forks by tty, remote env, and a 150ms window: PTY, pipe, exec-server — and only an early death can retry by policy

Inside OpenAI Codex 10 min →