Start from a skeleton
Almost every good voice-agent prompt answers five questions. Use the section headings — they cost nothing and keep long prompts editable:Tactics that matter on a phone call
Specific beats general
Vague instructions produce vague agents. Name the exact behavior you want:Write for the ear, not the eye
Callers hear the agent — they can’t skim or re-read. Tell the agent to keep spoken turns short, ask one question at a time, and say how to read data aloud:Confirm anything you’d hate to get wrong
Speech recognition mishears names, digits, and addresses. Build read-back into the flow:Script the unhappy paths
The happy path writes itself; calls are won and lost everywhere else. Give the agent a line for each situation you can foresee — the wrong number, the furious caller, the question you can’t answer:Always give the call somewhere to go
Every agent needs a hand-off path — a transfer number, a callback promise, or both. The prompt editor warns when it can’t find one.Call actions are plain prompt lines
Transfers, keypad presses, hold, and hang-ups need no separate configuration — describe them where they belong in the flow:Facts belong in knowledge, behavior in the prompt
Don’t paste your website into the prompt. Attach a knowledge base and the agent searches it mid-call — the prompt stays short, and updating a policy doesn’t mean re-editing the script. Keep the prompt for identity, flow, and rules; push catalogs, FAQs, and long policy text into knowledge.Personalize per call with dynamic config, not placeholders
Prompts have no template-variable system — a leftover{{customer_name}}
from another platform will be read as literal text, and the builder
flags it as an unresolved placeholder. To vary the prompt per caller
(VIP routing, logged-in user context), rewrite it at call time with
dynamic call config.
Write in the language you want to hear
The prompt can be written in any language, and the agent follows it. Which language the agent speaks is set separately — the primary language starts the call, and any additional languages switch automatically when the caller uses one.Templates
Three complete prompts to copy, then make yours: swap in your business facts, numbers, and policies.Front-desk receptionist (inbound)
Order support with a lookup tool (inbound)
Attach an API connection or connected app for the order lookup, and a knowledge base holding the returns policy.Appointment reminder (outbound)
For outbound scripts, also set who speaks first and voicemail handling in advanced call behavior — the prompt covers the conversation, the settings cover the pickup.Iterate until it survives real callers
No prompt is right on the first draft. The loop that works:- Talk to it. Click Talk in the builder and probe the edges yourself — interrupt it, go off script, mumble a phone number. This is the fastest tweak-and-retry loop.
- Simulate calls. An AI caller runs whole conversations against your agent, scenario by scenario.
- Build a validation set. Turn the scenarios you care about into a repeatable suite you rerun after every prompt change.
- Split-test in production. When two phrasings both seem fine, let real calls decide.
Next steps
Build your first agent
The builder end-to-end: prompt, engine, voice, tools, deploy.
Knowledge bases
Give the agent facts to search instead of a longer prompt.
Dynamic call config
Rewrite the prompt per call from your own backend.
Every agent setting
Supervision, who speaks first, voicemail, silence check-ins, and more.
