> ## Documentation Index
> Fetch the complete documentation index at: https://docs.zeroruntime.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# System Instructions & Greeting

> Define your agent's role and tone, and set the first thing it says on a call.

Both settings are on the **Agent** tab. The **System Prompt** tells the agent how to behave for the whole conversation. The **Welcome Message** is the first thing it says when a call starts.

## System Prompt

The **System Prompt** defines the agent's role, behavior, tone, and instructions. It is the only required field on the Agent tab.

A good voice prompt covers:

* **Role**: who the agent is and who it serves.
* **Goal**: what a successful call looks like.
* **Tone**: for example concise, friendly, and plain language.
* **Rules**: what to avoid, when to use tools, and when to end the call.

```text Example theme={null}
You are Maya, a support agent for Acme Internet. Help callers fix connection
issues and check their bill. Keep answers under two sentences and avoid jargon.
If the caller asks for a human, tell them you'll transfer the call.
```

<Tip>
  Write for the ear. Short sentences, no markdown, and no lists read best when spoken aloud.
</Tip>

### Improve with AI

Select the sparkle icon (**Improve with AI**) to rewrite your prompt into a more complete, structured version. When it finishes, select **Accept** to keep it or **Discard** to go back to your text.

## Welcome Message

The **Welcome Message** is the first message the agent speaks when a call starts.

```text Example theme={null}
Hi {{user_name}}, thanks for calling Acme Internet. How can I help you today?
```

| Setting | What it does |
| - | - |
| **Enabled** toggle | Turns the welcome message on or off. When it is off, the agent follows the system prompt. If the prompt doesn't define an opening line, the agent waits for the caller to speak first. |
| **Allow Users to Interrupt the Welcome Message** | Lets the caller talk over the greeting. The agent stops speaking and listens. |

<Warning>
  Turning the welcome message off clears its text in every language.
</Warning>

<Tip>
  Keep the greeting short and end it with a question, so the caller knows it's their turn to speak.
</Tip>

## Personalize with variables

Both fields support variables, for example `{{user_name}}`. Select **Insert Variable** above a field, or type `{{variable_name}}` directly.

Variables are highlighted in the editor. A name that isn't defined is flagged, and the draft can't be committed until you fix it. Define variables and their test values in [Variables](/agent-builder/agent/variables).

## Translate to other languages

If the agent has more than one [language](/agent-builder/agent/languages), both fields are stored separately for each language. Use the language selector at the top of the tab to switch between them.

Select **Translate to All Languages** under a field to translate it from the selected language into every other configured language.

<Note>
  If you edit the system prompt in one language and then switch languages without translating, the builder translates your edit into the other languages automatically.
</Note>


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