> ## Documentation Index
> Fetch the complete documentation index at: https://docs.phinite.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Capture Variables in Agent Node
Capture variables can be defined in three different ways, each serving a specific use case.
## Variable Definition Methods
Hardcode a static value
Reference an existing variable
Capture dynamically through conversation
## AI Derived Variables
AI Derived variables are automatically captured through the conversation between the agent and the user based on the description you provide.
### How It Works
**For Master Agents:**
* No need to explicitly mention variable capture in the agent prompt
* Simply add the variable name and provide a clear description
* The agent will automatically extract and store the value during conversation
**For Child Agents:**
* You must specify in the prompt which session variable to store the captured value
### Best Practices
Provide detailed descriptions including data type and format requirements:
```text Example: Phone Number theme={null}
Variable Name: phone_number
Description: A valid 10 digit phone number with country code and a '+'
```
```text Example: SQL Queries theme={null}
Variable Name: sql_queries
Description: Proper SQL queries as a Python list
```
Include the expected data type in your variable description for better accuracy.
## Referred Variables
Referred variables allow you to copy the value from an existing session variable. This is useful when you need to pass data between agent nodes or reuse existing values.
Simply select the source variable from the available session variables.
***
## Fixed Value Variables
Fixed Value variables contain static, hardcoded values that remain constant throughout the workflow.
### Configuration
1. **Value**: Enter the static value for the variable
2. **Description** (optional): Add a description for your reference
Ensure data type consistency when setting fixed values. The value should match the expected data type for downstream operations.