# Perplexity - Prompt Guide

> Learn to write effective prompts for the Agent API.

- Website: https://docs.perplexity.ai/guides/prompt-guide
- Category: [LLM Resources](/category/llm-resources/index.md)
- Added: 2026-10-01
- Updated: 2026-10-01
- Curated by: Harsh Chhajer
- Page: /resources/perplexity-prompt-guide/

## Understand Agent API Prompts

You will learn how to write effective prompts specifically for the Agent API. This guide explains how prompts influence tool selection, search query generation, and final responses.

## Use Instructions Parameter

Use the instructions parameter to set the role, tone, formatting, and grounding rules for your agent. These instructions apply on every turn of the agent loop, regardless of the user's question.

## Optimize Input Parameter

The input parameter holds the actual question and seeds the first search query. Specificity here directly improves retrieval, helping you get more accurate and relevant results.