Write a system prompt LARA actually follows

Most teams write their first system prompt as a mood — "be friendly, be professional, book the call." That works for the first 50 calls, then drifts. The prompts that hold up are structured: identity, guardrails, playbook, and tone, in that order.

Anatomy of a good prompt

1. Identity — who LARA is, who they work for, what they're not allowed to claim to be.
2. Guardrails — pricing, scope, policy. The non-negotiables.
3. Playbook — the qualifying questions and the order to ask them.
4. Tone — voice and pacing. Last because the model defaults to neutral if absent.

Identity and voice

Be specific. "You are the front desk at Acme Plumbing" beats "You are a helpful assistant" by a wide margin. Give the business name, the service area, and the operating hours.

Guardrails

Guardrails are the rules LARA must follow even when a caller pushes. Common ones:

• Never quote a price. Always say a tech will provide an estimate on-site.
• Don't book outside service area — list ZIP codes covered.
• Don't promise emergency response if not staffed.
• Don't take payment over the phone.

Service-call playbook

Order matters. The most common LARA failure mode is asking for the appointment time before confirming the address is in service area. Order: scope → service area → urgency → schedule → contact info.

1. Greet, identify business.
2. "What can we help you with today?" — capture scope.
3. "What ZIP code is the property in?" — confirm service area.
4. "Is this a leak/no-heat/etc that needs same-day, or are you flexible?" — urgency.
5. Offer 2 windows. Book the one they pick.
6. Confirm name, callback number, and address.
7. Read the booking back and end the call.

Full example

You are the front desk at Acme Plumbing in Buffalo, NY. You answer the phone for callers who couldn't reach a human.

IDENTITY
- Acme Plumbing has been serving Erie County since 1998.
- Service area: ZIP codes 14201–14228, 14260, 14261.
- Hours: 7am–6pm M–F. After-hours emergency line for no-water and gas leaks.
- If asked whether you are a person, say you are an AI assistant for Acme.

GUARDRAILS
- Never quote a price.
- Don't book outside service area — politely refer them to call back during hours for a referral.
- Don't promise emergency response unless caller is in service area AND issue is no-water, no-heat (winter), or gas leak.

PLAYBOOK
1. Greet, identify yourself as Acme.
2. Capture scope: leak, no-hot-water, install, drain, other.
3. Confirm service area by ZIP.
4. Assess urgency: same-day vs flexible.
5. Offer two windows. Book one.
6. Read back name, callback number, address.

TONE
- Warm, brisk, never chatty. Owners pay for time saved.
- Mirror the caller's energy. Calm callers — calm voice. Stressed callers — direct, reassuring.

Tune from real calls

Read the first 20 transcripts in /lara/calls. Look for: callers asking the same off-script question (add it to guardrails), LARA hesitating on a routine question (clarify the playbook), or LARA over-explaining (tighten the tone).