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Agent Core is the left-hand pane of the agent editor - the column that stays on screen whichever tab you have open on the right. It tells Vocily who the agent is, how it should behave, what it says first, and which variables it can use while talking to a customer. Because one agent can run across multiple channels, Agent Core should describe the agent’s core job and behavior. Channel-specific setup, such as phone numbers, web widgets, and WhatsApp assignment, lives in Deploy.
The pane folds. Use the control in its top-right corner to collapse it to a strip of four icons - Greeting, Purpose, Style, Call Flow - and click any icon to unfold it at that box. It folds on its own when Lily takes half the screen.

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What Agent Core controls

Agent Core is the pane you use for the agent’s most important conversation settings:

Greeting

Write the opening message. It is spoken in the agent’s primary language.

Prompt sections

Write the agent’s Agent Purpose, Response Style, and Call Flow.

Variables and defaults

Add reusable variables such as customer names, booking details, or other values the agent should personalize.

References to tools

Reference connected tools and API data inside the prompt when the agent needs them.

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Write the greeting

The first part of Agent Core controls how the conversation starts.
Language is not set here any more. The primary language, the languages the agent may switch into, and when it is allowed to switch all live in the Language pill at the top of the editor. See Language.There is no separate greeting language: the greeting is always spoken in the primary language, because it happens before the caller has said anything.

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Greeting Message

Write the first message the agent says when the conversation begins. Keep the greeting short, identify the agent or business clearly, and give the customer an obvious next step.
If the greeting includes a custom variable such as {{customer_name}}, it appears in Prompt Variables & Defaults.

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Write the prompt sections

Agent Core splits the prompt into three focused sections.

Agent Purpose

What this agent is trying to accomplish and what it should know.

Response Style

How the agent should speak, answer, and handle uncertainty.

Call Flow

The step-by-step conversation path the agent should follow.
Use the sections for different kinds of instruction:
  • Put the agent’s role, goal, and important business context in Agent Purpose.
  • Put tone, answer style, boundaries, and uncertainty handling in Response Style.
  • Put the order of the conversation in Call Flow.
Do not write language rules into any of the three boxes. An instruction like “reply in Hindi if the caller speaks Hindi” competes with Vocily’s own language switching, and which one wins is not predictable. Which languages the agent may reply in is derived from the Language pill and added to the prompt for you.
For example, an appointment agent might use:
  • Agent Purpose: Help customers find and book the right appointment.
  • Response Style: Keep replies short, ask one question at a time, and do not invent availability.
  • Call Flow: Understand the appointment type, collect the preferred time, check availability, confirm the booking, and summarize the next step.
The editor supports normal writing and simple formatting. You can paste structured text, then use the toolbar to format headings, bold text, lists, and numbered steps.

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Use variables and defaults

Variables let one agent personalize conversations with values that can change by customer, campaign, API result, or test run. Add a custom variable with double braces:
When Agent Core sees a variable in the greeting or prompt, it lists that variable under Prompt Variables & Defaults. Use that area to:
  • Select Add Default when the variable is already in the prompt and you want a fallback value.
  • Select Add to create a variable directly.
  • Edit or delete variables that should no longer be used.
Default values are fallbacks. If Vocily receives a real value for the variable during a conversation, the live value should be used. If no value is supplied, the default keeps the agent from sounding incomplete. For a deeper explanation, see Variables and default values.

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Reference tools and API data

Agent Core can also reference the agent’s tools and the data they return, so the agent knows they are available in the conversation. The editor renders each reference as a pill as you type. There are four formats:
Use these only after the tool exists in Tools. Keep the instruction clear: tell the agent when to use the tool, what information to collect first, and what it should say if the action cannot complete.

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Save and test

Select Save Changes after editing Agent Core. Saving stores the draft you are editing - it does not change what customers hear. Publish the draft and make it live when you are ready (see Versions). After saving, test the most important parts:
  • The greeting sounds natural and uses variables correctly.
  • The agent’s language set behaves as expected - it greets in the primary language and follows a caller who switches.
  • The agent follows the Call Flow instead of skipping steps.
  • Any tool references are only used when the matching tool is configured.
Use Test to try the agent by chat, browser voice, or a real phone call before sending customers to it.

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Let Lily write it

Lily can draft or rewrite any of the four boxes. Her suggestions arrive as a word-level diff in place of the box itself, so you read the change where the text lives and accept or reject each section on its own. Nothing is written until you accept.

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What’s next

  • Set the languages the agent speaks in Language.
  • Configure the model and response parameters in Intelligence.
  • Add tools and knowledge bases in Tools.
  • Choose the agent’s TTS voice in Voice.
  • Connect the agent to channels in Deploy.