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

# Best Practices

> Guidance for working with variables

<Info>
  This page covers key constraints and patterns for variables. Additional best practices from the Hamsa engineering team will be added here over time.
</Info>

## Variable Naming

All variable names must be **snake\_case** (lowercase letters, underscores, starting with a letter):

```
✅ customer_name
✅ account_balance
✅ is_verified

❌ customerName     (camelCase not accepted)
❌ Customer-Name    (kebab-case not accepted)
❌ customer name    (spaces not accepted)
```

## Extraction Availability

Extracted variables are only available **after** the node that collects them. Do not reference an extracted variable in a transition or node that comes before it in the flow.

Global node conditions cannot reference extracted variables — use system variables or custom variables there instead.

## Single Prompt Agents

Custom variables are the only type available in single prompt agents. Extracted variables and static variables are not supported. Custom variables become `params` in the agent configuration and must be passed when initiating a call.

## Testing Tool Extraction

Always test a tool call first to see its actual response before configuring extraction. Use the path selector to pick JSONPath expressions from the real response — avoid writing JSONPath by hand.

***

## Next Steps

<CardGroup cols={2}>
  <Card title="Custom Variables" href="./custom-variables">
    Define variables in your agent configuration
  </Card>

  <Card title="Extracted Variables" href="./extracted-variables">
    Collect data from conversations and tool responses
  </Card>

  <Card title="Troubleshooting" href="./troubleshooting">
    Diagnose common variable issues
  </Card>

  <Card title="Examples" href="./examples">
    See full flow examples with variables
  </Card>
</CardGroup>