How should I write my AI agent's instructions, and how long should they be?

Less is more. A longer prompt does not make the agent better, and you do not need a ten page prompt from ChatGPT. A short block of text gives the AI enough context to know what to do at a high level, without covering every if-then. A short prompt is also easy to maintain: you know where to go to change a behavior, while a long prompt you have not read is hard to troubleshoot.

Avoid conflicting or confusing instructions, such as always do this in one place and sometimes do that in another.

The AI is very literal and only does what it is told. If an instruction is not in the prompt, it will not do it. For example, an agent told to ask for the service address or city may only ask for the street number, and it will not confirm the address unless you tell it to. Spell out exactly what you want, for example: ask for the full street address, then spell the street number and street name back to the caller and confirm they are correct. In the other direction, if you tell it to always ask whether the problem is plumbing or electrical, it will ask even when the caller already said. Avoid absolutes such as always, and add conditions, for example: ask only if you cannot tell from what they describe, otherwise infer it.

What to include: the AI already has general knowledge, so leave that out, along with files on how to sell or conversion frameworks. Include the specifics of the business: business name, phone number, hours, address, how long you have been in business, licensed and insured, prices or price ranges, the process to get started, and FAQs. A clean format is questions and answers under a heading like FAQs (for example: What is the cost? Half day charters start at $500), but any format works, and you can paste a block of text from the website. Put short answers to repetitive questions, such as a meeting link, in the instructions. Say exactly when to use each tool.

Prompt or files: you can upload files, which is useful for something like a product catalog the AI should reference. Otherwise put the facts directly in the prompt, so you can see everything the AI knows on one page.

Then set the greeting for inbound or outbound and use Test to try it. Give the AI one piece of information at a time to see how it uses its tools and moves through each field, and edit as you go. The Chat test mode simulates SMS or the website widget.