Writing Instructions
Theinstructions decide who the agent is, what it’s after and how it behaves. Good instructions cover five things.
1. Identity & Role
2. Goal & Context
3. Tone & Style
4. Handling Scenarios
5. Boundaries
Complete Example
Model Selection
Live
One voice model hears and speaks. A second model runs the agent’s actions, like calling your tools or handing off between crew members, andmodel picks it from live.llm in GET /v1/models (anything else returns 400). Left out, the call uses the entry marked default: true. Send mode: "live" with it, since a model without a mode runs Legacy.
Legacy
model picks the model that writes every reply, from legacy.llm in GET /v1/models.
Voice Selection
Live Voices
live_voice takes one of 13 voices: marin, quartz, ripple, vesper, willow, stone, gleam, meridian, bossa, tempo, beacon, delta, cinder. Leave it out and the call picks one for its language.
Legacy Voices
About 50 built-in voices, male and female. Pass a voice ID fromGET /v1/voices/builtin or GET /v1/voices as voice.
Language & Dialect Control
Live
stt_language(orstt_languagesfor several) sets the starting language and the default live voice. Use a code fromsupported_languagesinGET /v1/models; anything else returns400- The agent switches language only when your instructions allow it
Legacy
stt_language(orstt_languages) sets the speech recognition language, dialect included:en-GBvsen-US- The agent speaks only those languages. Instructions can’t add another
- Up to 78 languages. The exact set depends on the speech recognition and voice models
Temperature
temperature runs from 0 to 1 and defaults to 0.7. Lower is steadier, which suits confirmations. Higher varies more, which can suit sales.
supports_temperature is false in GET /v1/models ignores it.
First Sentence
The opening line, spoken when the call connects. Legacy says it word for word; Live may reword it slightly.Best Practices
- Name the scenarios and what to do in each. “Be helpful” tells the model nothing.
- Say what the agent must never do.
- Personalize with
{{variable}}placeholders. - If you want “sell, but don’t push”, say where the line is.
- Aim for 200 to 500 words.
- Test on a few calls and rewrite from the real transcripts before you scale.
Next Steps
Voice Library
Browse the built-in voices for each mode.
Function Calling
Give your AI tools to interact with your systems mid-call.