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Every endpoint on this page requires either a Clerk-issued JWT (Authorization: Bearer <token>) or an organization API key (x-api-key: pk_…). Anonymous calls return 401 Unauthorized. See Authentication for the full setup.
Each agent has a System Prompt that defines its behaviour. You can sprinkle placeholders into the prompt that are resolved at call-start time from two sources:
  • System variables — populated automatically by Agentix (date/time, channel context, telephony identifiers).
  • Custom variables — supplied by you under session_variables in the call-trigger request.

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How dynamic variable replacement works

Placeholders use double-curly syntax: {{variable_name}}. When a call starts, Agentix runs a templating pass over the system prompt before the very first message is sent to the model. Everything inside {{…}} is replaced with the resolved value. The LLM never sees the placeholder — it only sees the final, hydrated prompt. Prompt template: 
Hello {{customerName}}, you are calling about {{orderInsight}}.
Sent to the LLM at runtime: 
Hello Alex, you are calling about order #88291 (placed 2026-05-09, status: shipped, tracking AE998123).
Rules to remember
  • If a placeholder has no matching value, it is left as-is (e.g. {{customerAge}} stays literal). Instruct the LLM to ask the user for it rather than leaving the literal placeholder in dialogue.
  • Replacement happens once per session, at the start. Mid-call value changes are not propagated.
  • Values are always rendered as strings. Pass pre-formatted strings (currency, dates) if you need them styled.

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System variables (provided automatically)

These keys are populated by Agentix at call-start — you don’t pass them in. They cover date / time, channel context, and telephony identifiers.

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Date and time

PlaceholderHow it’s computedExample output
{{system.year}}now.getFullYear() (UTC server)2026
{{system.date}}now.toISOString().split('T')[0] (UTC date)2026-05-08
{{system.time}}now.toLocaleTimeString() (UTC server locale)10:28:42 AM
{{system.now}}now.toISOString() (UTC)2026-05-08T10:28:42.123Z
{{system.dubai.now}}now shifted to Asia/Dubai (UTC+4) → ISO2026-05-08T14:28:42.000Z
Use these for time-aware behaviour (“a viewing this week”, “the order placed 3 days ago”, “good morning/afternoon”).

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Channel context

PlaceholderResolves toExample
{{system.platform}}Session platformvoice / chat / whatsapp
{{system.medium}}Session mediumphone / web
{{system.direction}}Call directioninbound / outbound

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Telephony and session identifiers

PlaceholderResolves toExample
{{system.incoming.phonenumber}}Incoming number (or empty)+97142000000
{{system.outgoing.phonenumber}}Outgoing number (or empty)+971501234567
{{system.customer.phonenumber}}Always points to the customer’s number, regardless of direction+971507654321
{{system.roomname}}LiveKit room name (or empty)voice-room-7f3b…
{{system.sessionId}}Session IDsess_abc123
Fallback rule: any non-system.* {{key}} is pulled from session_variables. If the key is missing or empty, instruct the LLM to ask the user for it rather than leaving the literal {{key}} in dialogue.

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Custom variables

You define these yourself. Anything you send under session_variables in the trigger request becomes available as {{key}} in the prompt. A typical canonical set for an outbound use case:
VariablePurposeExample value
customerNameWho the agent is calling"Alex Morgan"
contextSummaryPre-baked summary of the reason for the call"Order #88291, placed 2026-05-09, status shipped, ETA 2026-05-14"
objectiveWhat the agent should accomplish"Confirm delivery slot and capture preferred time"
crmContactIdMapping key back to your CRM record"CRM-7728"
The CRM mapping key (crmContactId above) is critical: it’s the thread you’ll use later to map the Agentix call back to your own contact record. It is echoed back verbatim in the webhook payload under metadata.sessionVariables — see Webhook events.

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Designing a system prompt that uses these variables

A prompt template that exercises both system and custom variables: 
You are calling {{customerName}} on behalf of Acme Co.

Today is {{system.dubai.now}}.

Context for this call:
{{contextSummary}}

Your objective:
{{objective}}

Conversation rules:
  - Greet the customer by name.
  - Stay polite and concise — keep the call under 3 minutes.
  - If the customer is unavailable, ask for a better time to call back.

When the objective is satisfied, thank the customer and end the call.
The corresponding session_variables payload at call time: 
{
  "customerName": "Alex Morgan",
  "contextSummary": "Order #88291, placed 2026-05-09, status shipped, ETA 2026-05-14",
  "objective": "Confirm delivery slot and capture preferred time",
  "crmContactId": "CRM-7728"
}
Build contextSummary server-side by concatenating relevant fields from your DB. Sending one pre-formatted string keeps the prompt readable and lets you change the surface format without touching the agent config.

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Cheat sheet

TypePatternSourceExample
System{{system.now}}Agentix2026-05-13T11:02:14Z
System{{system.customer.phonenumber}}Agentix+971507654321
Custom{{anyKey}}session_variables.anyKey in trigger callAlex Morgan

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Next steps

Trigger an outbound call

Pass session_variables in the call-start request.

Post-call analysis

Configure structured fields that get extracted from the transcript.