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02 · Reasoning Cost

First-Pass Execution

The model completing a task correctly on the first attempt because context was clear enough to skip interpretation loops.

First-Pass Execution is the gold standard for prompt engineering and system design. It means the model read the prompt, understood the task, and produced the correct output without needing clarification, without backtracking, and without the user having to send follow-up corrections. First-Pass Execution doesn't depend on model intelligence — it depends on context quality. A less capable model with perfect context will achieve First-Pass Execution more often than a frontier model with messy context. Every follow-up turn you don't need is money saved and time recovered.

Example
A product manager asks an AI to generate a PRD. First attempt: "Write a PRD for the new notifications feature." Result: a generic document that requires three rounds of revision. Second attempt: "Write a PRD for push notification preferences. Users: mobile iOS/Android. Core requirement: per-channel opt-in/opt-out (email, push, SMS). Include: user stories, acceptance criteria, edge cases, data model. Format: [template]." Result: a usable first draft requiring only minor edits. The second prompt achieved First-Pass Execution. The first one cost four turns to reach the same quality.

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