If you already use GPT or Claude and your day is browser -> chat box -> editor -> copy/paste, the first mistake is treating Codex like just another chat tab. Write AGENTS.md before you talk about enterprise Codex. AI is starting to take not just code tasks, but the scraps of time you lose switching windows.
The visible cost of getting this wrong is simple: you keep manually hauling context into every tool and pay for another round of rework. The hidden cost is worse: you keep using Codex in the wrong place, so the tool feels messy when the real gap is process. Most people think they need a stronger model. What they usually need is fewer window switches.
That is the point Cisco and OpenAI keep converging on. OpenAI says AGENTS.md tells Codex how to understand the repo, what tests to run, and which project rules to follow. It pairs that with setup scripts, environment settings, and a plan-first workflow: Ask Mode first, Code Mode second. Cisco's reported gain was similar: Codex worked better when it acted like a teammate following a written plan humans could review. Cisco and OpenAI redefine enterprise engineering with Codex [C001].
So the order is not "buy seats, then figure out process." The better order is: write the project rules, setup steps, and reviewable plan first, then decide how much Codex access you actually need. Boundary: this is based on Cisco and OpenAI's published workflows, not a benchmark on one laptop or one team. If someone in your orbit is shopping for AI tools first, send them this.