GuidesAI agents
Write your agent’s instructions
What to put in Role, Tone, Always, Never and Additional context, how they become the agent’s instructions, and what Crulon tells the agent on every call.
The Persona & Instructions section decides how your agent behaves more than any other setting. This page shows how the five fields turn into instructions, what to write in each, and what to leave to other settings.
- Where
- AI Studio > Agents > your agent > Persona & Instructions
- Takes effect
- When you publish the agent
- Check it
- Effective prompt, at the bottom of the section
How the fields add up
The builder joins the five fields into one set of instructions, in a fixed order. Open Effective prompt at the bottom of the section to see the result.
- Role
- the front desk for North Valley Heating & Air, a family heating and cooling company
- Tone
- Friendly · Concise · Patient
- Always
- Get the caller’s name and the service address before opening a ticket Read back dates, times and addresses before you finish
- Never
- Quote prices for repairs: a technician prices the job on site Promise a same-day visit
- Additional context
- Office hours are Mon–Fri 7am–6pm. We serve Tucson, Marana and Oro Valley. A no-heat call with a baby or elderly person in the home is urgent.
Effective prompt
You are the front desk for North Valley Heating & Air, a family heating and cooling company. Tone: Friendly, Concise, Patient. Always: - Get the caller’s name and the service address before opening a ticket - Read back dates, times and addresses before you finish Never: - Quote prices for repairs: a technician prices the job on site - Promise a same-day visit Additional context: Office hours are Mon–Fri 7am–6pm. We serve Tucson, Marana and Oro Valley. A no-heat call with a baby or elderly person in the home is urgent.
What Crulon adds on every call
Your instructions aren’t all the agent is told. Around them, Crulon adds:
- Your business name, from Identity: the agent is told it answers calls for that business.
- Phone manners: it’s on a phone call, so it keeps replies to one to three sentences unless the caller asks for more, and asks one question at a time.
- Your Tools, each with its instructions for this agent. See Give your agent Tools.
- Who’s calling: the caller’s number, and whether it matches a customer on file, by name and status only. When one customer matches, their account is chosen for the agent’s Tools. When several do, none is, and the agent is told not to guess.
- The date, time and time zone, unless you turned this off in Behavior.
- Where it can send callers, with your “when to send callers here” sentence and hours for each destination, and your goodbye phrases.
- What your documents say, when something in them matches what the caller asked. See Give your agent knowledge.
So there’s no need to write “you’re on the phone, keep it short” or list your Tools in the instructions: Crulon does that.
On Live agents
A Live agent works in two parts: one talks with the caller, and the other does the work, such as using Tools and checking your documents. Effective prompt shows both: What the voice hears and What the backend follows.
- The voice gets your Role, Tone and the start of your Never rules.
- The part that does the work gets everything, including Always and Additional context.
- Live agents are also told not to state addresses, phone numbers, prices or policies unless they came from your instructions, a Tool, your documents or the caller.
So on Live, keep Never short and put the most important rules first. See Classic and Live.
Write each field
Role
One line, starting “You are …”: who the agent is and for whom. Give it a job, not a personality.
| Instead of | Write |
|---|---|
| a helpful AI assistant | the front desk for North Valley Heating & Air |
| a customer service bot | the after-hours line for Ridge Property Management, taking maintenance requests |
Tone
Pick two or three from Friendly, Professional, Concise, Warm, Direct, Empathetic, Patient and Confident, or type your own, up to 40 characters. More than three pull against each other. Concise helps on almost every line: callers can’t skim speech.
Always
Rules for every call, one per line. Each should be something you could check in a transcript.
- “Get the caller’s name and a callback number before ending the call.”
- “If the caller is upset, acknowledge it before solving the problem.”
- “Before sharing account details, check the caller’s name and the service address match the account.”
Avoid wishes like “be helpful” or “give great service”: they don’t change anything.
Never
Hard limits, one per line. Say what to do instead, so the agent isn’t stuck.
| Instead of | Write |
|---|---|
| Don’t talk about prices | Never quote repair prices: say a technician prices the job on site |
| No legal advice | Never advise on lease disputes: offer to take a message for the property manager |
Additional context
What the agent should know: your hours, service area, how a typical job works, and how to handle the cases that trip people up. Write it as you’d brief a new receptionist.
Keep it to what the agent needs on most calls. Longer reference material, such as price lists, policies or FAQs, belongs in Knowledge, where the agent finds the part that matches the question.
Check who’s calling
When the agent has a Tool attached, Crulon tells it the caller’s number and whether it matches a customer, before the call starts. A matching number isn’t proof of who’s speaking: phones get shared and numbers get passed on.
If the agent can share account details or make changes, add a rule to Always, such as:
Before sharing account details or making a change, ask for the name and service address on the account, and check they match.
For each Tool that changes something, also set what the agent confirms first in the Tool’s Confirmation. See Checking with the caller first.
What belongs somewhere else
Some things work better in their own settings than in the instructions:
| To | Use |
|---|---|
| Say a fixed opening line | Greeting |
| Send callers to your team or another number | Handoff: the agent never dials a number written in the instructions |
| Answer from long documents | Knowledge |
| Look things up or make changes | Tools, with instructions for each Tool |
| Close at certain hours | Destination hours, or a Time Condition in your Call Flow |
| End the call politely | End call: goodbye phrases and the farewell |
Optimize
Optimize rewrites your five fields. Choose a goal, then select Optimize:
- Clarify: clearer wording, the same behaviour.
- Shorten: about a third fewer words.
- Add guardrails: one to three extra limits in Never or Additional context, without inventing policies.
You see each field before and after, and a one-line summary. Select Apply changes to use it, or Keep original. Nothing changes on calls until you publish. Optimize can run up to 60 times an hour.
Start from a template
Apply template fills all five fields with a starting persona, replacing what’s there. Edit it to fit your business. If you haven’t published, Discard draft undoes it.
Test and improve
- Write the fields, then select Talk in browser and play a caller: a simple request, a confused one and an awkward one.
- Read the transcript. Where the agent went wrong, change one thing: usually a line in Always or Never.
- Test again, then Publish with a note about what changed.
When a rule doesn’t stick, make it more specific (“say a technician prices the job on site”) rather than louder (“NEVER EVER quote prices”).
If something goes wrong
Make it specific and checkable, and say what to do instead. On Live agents, move it nearer the top of Never, since the voice only hears the start of them.
Add the facts to Additional context or Knowledge, and add a Never rule such as “Never guess an answer: offer to take a message.”
Add Concise to Tone, and an Always rule such as “Answer the question, then stop.”
Optimize can run up to 60 times an hour. Wait a few minutes, then try again.
Last updated 18 Oct 2026