Site widget → Customize → Assistant Instructions is a free-text box that shapes how the assistant behaves. Whatever you write there applies everywhere the widget runs — your website, your portal, every embed — and it takes no code.
What to put in it
Think of it as briefing a new support hire on their first day. The things that are true about your business but are not written in any one article:
You are the assistant for Tony's Guitars.
Prices are in EUR and include VAT. We ship within the EU only.
For repair requests, point people to repairs@tonysguitars.example.
Never promise a delivery date; say "usually 2-4 working days".
Keep answers short — two or three sentences unless asked for detail.Good candidates:
Tone and length. "Be brief and direct." "Warm, but never chatty."
House facts. Currency, shipping regions, opening hours, return window.
Handoff rules. When to stop trying and give someone a human. This is the one most people forget, and the one visitors notice most.
Things not to say. "Do not speculate about our roadmap." "Never quote a price for enterprise plans; ask them to book a call."
Language. "Always answer in French, even if asked in English."
What it cannot do
The instructions sit inside a larger prompt with rules that come first, so a few things are out of reach:
It cannot make the assistant cite articles differently, or stop it citing them.
It cannot invent knowledge. Telling it "you know our pricing" does not give it your pricing — publish an article, or register a tool.
It cannot override the safety rules that stop page content and tool results being treated as instructions.
If you write something that conflicts with those, the built-in rules win.
Keep it short
A page of instructions is worse than a paragraph. Everything you write is sent with every question, so a long brief costs tokens on every message and dilutes the parts that matter. The limit is 2000 characters, but most projects need a fraction of that.
If you find yourself explaining a product in the instructions, that belongs in a help article instead. Instructions are for how to behave; articles are for what is true.
Testing a change
The Live Preview beside the form on the Customize tab uses the same instructions as your real widget, so you can save a change and immediately ask it something. It answers exactly as the widget on your site would.
It applies retroactively
There is nothing to redeploy. Save the field and the next question anyone asks — on any site running your widget — uses the new instructions.