What Answer instructions are
Answer instructions — what other tools call a system prompt — are a set of rules and background that go out with every message the AI writes. They shape how it introduces itself, how formal or casual it sounds, what it will and will not discuss, and how it handles awkward cases.
You will find the field at Brand → Vex → Personality → Answers, labelled Answer instructions. The description under it reads: "Extra instructions sent with every AI prompt. Use this to define tone, rules, or specific information the AI should always know." The instructions belong to that one agent, so a second brand has its own set and nothing is shared between them.
What to write in them
Think of it as the briefing you would give a new support hire on their first morning. Cover:
- Role: what the agent is and who it is for ("You are Vex, a support agent for Acme Corp, helping customers with billing and product questions.")
- Tone: formal, friendly, concise, warm — pick one or two words and stay with them.
- Topics to avoid: competitors, legal advice, medical advice, whatever is off-limits for you.
- Things to always do: sign off with a contact address, use the visitor's name, point at the knowledge base first.
- What to say when it does not know: the behavior itself is a separate setting on the Human hand-off tab (see below), but you can reinforce the wording here.
- General knowledge: Vex states facts — about your company, your products, prices, policies and delivery, and about the visitor's topic — only from this brand's own data and articles, and never adds anything from its own general knowledge. Asked what something is or how it works, it answers only from your data, or says it has no more detail on that. This is the same for every brand, and these instructions cannot switch it off.
Tone settings beyond the instructions
One toggle on the same Answers tab changes the voice without you writing a word: Emoji Usage. By default the AI uses emojis to keep conversations friendly; tick "Disable emojis in AI responses" for a more formal tone.
Your company name is no longer set here. It is a brand setting, at Brand settings → General, alongside your website and a description of the business — and Fill from website can write all three for you from your website address. The AI reads them, so it is worth filling in properly even though it is not on this screen.
When Vex doesn't know the answer
On the Human hand-off tab, Offer a person when the AI has no answer decides what happens when nothing relevant turns up in this brand's knowledge. There are two choices:
- Politely decline (recommended): the agent tells the visitor it does not have information about that topic. It does not guess and does not make things up. Safest for most setups.
- Connect to a person: if someone from your team is online, the visitor is connected to them right away, with no question asked first. If nobody is online, the agent politely declines instead.
The second option is greyed out until the Visitor asks the AI for a person switch above it is on, with the hint "Switch on 'Visitor asks the AI for a person' to use this option." There is no third "answer anyway from general knowledge" option — that choice does not exist in the product.
Tell visitors how to sign in
Also on the Answers tab is How visitors get identified. API tools and workflows can be switched to Only for identified visitors, so they work only for customers your website signed in through Yaplet.identify (see Identify your logged-in users with custom data). When a visitor who is not identified asks for one of them, the AI does not run it. It passes this text on instead, in its own words and in the visitor's language.
Write where and how your customers sign in, for example "Log in at example.com/account, then open the chat on any page and ask again." It is plain text, at most 1,000 characters. Left empty, visitors are told the standard sentence: "To use this, please sign in to your account on our website and open the chat from there, then ask again." Next to the switch on an API tool and on a workflow's Starts when card, a panel shows the text visitors get right now, with an Edit this text link that brings you back here. A single Call an API step does not use this text: a visitor who is not identified takes the step's Failed exit.
Tips for effective instructions
- Be specific, not vague. "Be friendly" is hard to act on. "Use first names when the visitor introduces themselves, never say 'ticketing system', and keep replies under four sentences" is actionable.
- List what NOT to do. Restrictions usually land harder than positive instructions.
- Keep it short. A few tight paragraphs beat a page of prose — these instructions go out with every single message, and a long one dilutes the rules that matter most.
- Test after every change in the chat widget's preview.
Example instructions
You are Vex, a support agent for Acme Corp. Your job is to help customers with questions about our project management software.
Tone: Friendly but professional. Use first names when offered. Keep replies concise — 2–3 sentences max unless a step-by-step answer is needed.
Always: Suggest the knowledge base first. If you can't find the answer, say so clearly and offer to connect the visitor with a human agent.
Never: Discuss competitors. Give pricing advice beyond what's in the knowledge base. Make promises about features that aren't documented.
If asked about your technical nature, say: "I'm Vex, Acme's AI support assistant."Next step
Try your wording before real visitors see it: Test your chatbots before going live. To control when the agent escalates to a person, see Control when Vex hands off to a human.