Prompt agents

A prompt agent is a single agent driven by one prompt. It is the fastest way to something useful, and it is the right shape whenever the conversation does not have to follow a fixed path.

The prompt

The prompt is the agent's instructions and it is where most behaviour lives. If the agent does not ask for something, uses the wrong tone, skips a step or fails to confirm, the fix is almost always here rather than in a setting.

Write it like a brief for a new employee:

You are the receptionist for Acme Dental.

Your job: find out whether the caller wants to book, move or cancel an
appointment, then collect their full name and phone number.

Always: confirm the details back before ending.
Never: give medical advice, or quote a price.
If asked anything else: say a colleague will call back.

Replies are spoken aloud. Ask for one thing at a time, keep sentences short, and avoid anything that only makes sense in writing (lists, headings, symbols).

Who speaks first

first_speaker decides whether the agent greets or waits.

assistant - the agent opens with its greeting.
user - the agent stays silent until the caller speaks.

This is the most common cause of an agent that appears to do nothing, or that talks over a caller who has already started.

Turn-taking

endpointing.stop_secs is how long a pause has to last before the agent decides the caller has finished. Raise it if the agent interrupts; lower it if replies feel slow.

Silence

By default the agent waits indefinitely. Set silence_timeout_seconds above zero to have it nudge a silent caller, with idle_message as what it says and idle_max_prompts as how many times before it gives up and ends the call.

max_duration_seconds is a hard cap on call length regardless of what is happening.

Ending the call

end_call_phrases - things a caller says that end the call, matched literally.
end_call_enabled - lets the agent judge from intent that the caller wants to wrap up, rather than waiting for an exact phrase.
end_call_message - the farewell.

Speaking style

speaking_style controls how the agent sounds rather than what it says: whether it uses natural fillers while it thinks, whether it backchannels ("mm-hm") while the caller talks, and its overall style.

Voicemail

voicemail.enabled lets an outbound call detect an answering machine and leave voicemail.message instead of talking to a beep.

Compliance

compliance.redact_pii redacts personal data from stored transcripts. See Privacy and compliance.

What else an agent can have

Models and voices - which model, transcriber and voice.
Knowledge base - answer from your own documents.
Tools - take actions mid-conversation.
Variables and extraction - pass data in, capture data out.