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Prompts and welcome messages tell a DialNexa agent what to do and how the call begins. The prompt controls the conversation goal, the system prompt adds higher-level rules, and the welcome message controls the first spoken turn when the agent starts the conversation. DialNexa prompt editor showing the Welcome Message field above detailed Agent Prompt instructions.
The first sentence has a job: make the caller stay on the line long enough for the second sentence to matter.

Before You Begin

Write down the agent’s single objective, required facts, prohibited behavior, escalation rules, and a clear definition of success. Collect approved wording for sensitive or regulated statements.

Prompt Fields And Meaning

Write each field for a different purpose.

Variable Syntax Validation

The agent builder validates dynamic variable placeholders before saving, testing, or publishing prompt-related text. Use simple double-brace syntax such as {{first_name}}. Prompt text, welcome messages, and voicemail messages must be valid Handlebars template text. The validation message points to the first affected line and can report additional errors after that. Fix malformed variables before changing the prompt content itself. System prompt text is static. Put dynamic caller data in the main prompt, welcome message, voicemail message, default variables, batch CSV, workflow lead data, or API launch payload instead.

Conversation Start Modes

The caller speaks first. Good for inbound calls where the caller has a reason to call.

Write Prompt Instructions That Survive Real Calls

1

Name the caller goal

Tell the agent the single most important outcome.
2

Define what not to do

Add boundaries for speculation, pricing, escalation, or unsupported requests.
3

Use examples

Include phrasing for short answers, objections, wrong number, busy caller, and language switch.
4

Connect tools to intent

Tell the agent when to use functions, not just that functions exist.
5

Make the ending explicit

Tell the agent when to end, transfer, schedule, or summarize.

Prompt Review Questions

If success is vague, post-call fields and summaries will be vague too.
Use placeholders such as {{first_name}} and define defaults where needed.
Inbound and outbound openings usually need different wording.
Long prompts are sometimes necessary, but repeated rules and unclear sections make behavior harder to debug.

Verify The Prompt And Welcome Message

Test the normal path, an interruption, silence, an out-of-scope question, a correction, and a request for a human. Confirm the agent stays within scope and the transcript reflects the intended behavior.

Dynamic Variables

Add caller-specific values.

Single Prompt Agents

Use one instruction set.

Testing Agents

Test the first turn and edge cases.

Agent Prompts Video

Watch how to write focused agent instructions.

Welcome And System Prompt Video

Watch how the opening and core instructions work together.