System prompt explained: behavior, cost, and pitfalls
A system prompt is the hidden instruction block that shapes every LLM response. Here's how it works, what it costs, and the production pitfalls to avoid.
Tag · prompt-engineering
A system prompt is the hidden instruction block that shapes every LLM response. Here's how it works, what it costs, and the production pitfalls to avoid.
Fine-tuning trains a model on your data to shape behavior and output format. Here's when it beats prompting, what it costs in 2026, and when to skip it.
Your OpenAI bill isn't just input + output tokens. Thinking tokens, JSON retries, and prompt bloat quietly triple costs. Here's how to spot each one in your own app.