Question

You are building a customer support assistant that must always respond in a friendly, concise tone and never reveal internal pricing formulas. You want these behavioral rules to apply consistently across every turn of a multi-turn conversation, regardless of what the customer types. Where should you place these persistent instructions in your Messages API request?

Accepted Answer

In the system prompt (top-level system parameter)

Answer

In the first user message, prefixed to the customer's question

Answer

In an assistant message you prefill at the start of the conversation

Answer

Repeated in the max_tokens parameter description on every request