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The prompt is the most important part of your agent configuration. It tells the agent who it is, what it should do, and how it should behave during calls. A well-written prompt leads to natural, reliable conversations.
Prompt Structure
A good agent prompt typically includes these sections:
Background
Tell the agent who it is and set the context for the conversation.
Your name is Sarah. You are a scheduling assistant calling patients
to confirm their upcoming appointments at Downtown Medical Center.
Goal
Clearly state what the agent should accomplish on the call.
Confirm the patient's appointment for {{appointment_date}} at {{appointment_time}}.
If they need to reschedule, collect their preferred date and time.
Instructions
Provide step-by-step guidance on how the conversation should flow.
1. Greet the patient and introduce yourself.
2. Confirm the appointment date and time.
3. If they confirm, thank them and end the call.
4. If they need to reschedule, ask for their preferred date and time.
5. Confirm the new time and end the call.
Behavioral Notes
Add rules that shape how the agent speaks and handles edge cases.
- Speak conversationally. Do not list information — use natural sentences.
- Do not use markdown or formatting. You are on a phone call.
- If placed on hold, wait patiently. Do not hang up.
- If you reach voicemail, leave a brief message with the appointment details.
Using Parameters
You can reference dynamic values in your prompt using {{parameter_name}} syntax. These values are passed in when the call is created — either through the API or from a campaign CSV upload.
You are calling {{customer_name}} about order {{order_id}}.
Their email on file is {{customer_email}}.
Voice-Specific Tips
Voice agents behave differently from text-based AI. Keep these in mind:
Reading Numbers
Numbers need to be read digit by digit for clarity. Instruct the agent to read them slowly:
When reading a phone number, say each digit individually with a pause between groups.
For example, read 5551234567 as "five, five, five — one, two, three — four, five, six, seven."
When reading a price, say it in full. For example, "$1,295.50" should be read as
"one thousand, two hundred and ninety-five dollars and fifty cents."
Spelling Names and Emails
Names and email addresses are often misheard on a phone call. Instruct the agent to offer to spell them:
When providing a name, say it first, then offer to spell it.
Spell one letter at a time with a brief pause between each letter.
Handling Hold and Transfers
Agents may be placed on hold or transferred. Make this explicit:
If placed on hold, wait for the other person to return. Do not hang up.
If transferred to another person, introduce yourself and continue the conversation.
Avoiding Unnatural Output
Phone calls should sound like natural speech, not text output:
Do not use markdown, bullet points, or parenthetical notes in your responses.
Never say words in parentheses like "(pause)" or "(laughs)".
Speak in natural, conversational sentences.
Full Prompt Example
Here is a complete example prompt that incorporates the patterns above:
## Background
Your name is James. You are speaking on the phone with a customer
who you just called.
## Goal
Tell the customer about their upcoming delivery for order {{order_id}}
and confirm the delivery address.
## Instructions
1. Greet the customer and introduce yourself.
2. Let them know you are calling about their order.
3. Confirm the delivery address: {{delivery_address}}.
4. If the address is correct, thank them and end the call.
5. If they need to update the address, collect the new address
and read it back to confirm.
## Behavioral Notes
- Speak conversationally. Do not list out details — form natural sentences.
- Do not use markdown or formatting in your responses.
- Use casual filler words like "great" and "awesome" to sound natural.
- Do not use filler words when reading numbers or addresses.
- If placed on hold, wait patiently. Do not hang up.
- If you reach voicemail, leave a brief message with the order number
and ask them to call back.
- Read numbers slowly, one digit at a time.
Best Practices
- Be specific — vague prompts produce vague conversations. Tell the agent exactly what to do in each situation.
- Test with real calls — make a few test calls after writing your prompt to hear how it sounds in practice.
- Handle edge cases — think about what happens if the person does not answer, asks to be called back, or asks an unexpected question.
- Keep it focused — one prompt should cover one use case. If you need different behavior for different scenarios, use flow-based agents with separate prompts per node.
- Iterate — prompts rarely work perfectly the first time. Listen to recordings, spot issues, and refine.
