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Session variables in your flow can be categorized into several types based on how they are created and managed.

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Capture Variables

Capture Variables are automatically captured by the Agent during execution based on the description you provide. The Agent identifies and stores relevant information as the workflow progresses.

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Tool-Returned Capture Variables

These variables are returned by tools during execution, including both custom and predefined tools. For custom tools, simply return the variables in the capture_variables dictionary, and they will be automatically stored as session variables(each key stored as seperate session variable).

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User Variables

User Variables are defined in the API payload before executing an autonomous or conversational flow. These allow you to pass initial data into your workflow.

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System Variables

The following system variables are automatically set in every session:
  • workflow_id - A unique identifier assigned to each workflow execution
  • caller_number - Available during voice calls, containing the caller’s phone number

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Predefined Tool Variables

When using predefined tools, the entire output object returned by the tool is saved as a session variable.

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Example: Telegram Tool

Screenshot 2026 02 11 At 6 40 01 PM For the telegram.get_chat_member_count tool (from the Telegram integration), the complete output object is stored in the session and can be accessed using dot notation: 
telegram.get_chat_member_count.count
telegram.get_chat_member_count.chat_id

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Using in Custom Tools

You can access these variables in your custom tools like this: 
# Retrieve the entire output object
telegram_output = inputs.get('telegram.get_chat_member_count')

# Access specific fields
chat_id = telegram_output.get("chat_id")
member_count = telegram_output.get("count")
The session variable name follows the pattern: {tool_name}.{subtool_name}