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Custom variables are defined at the workflow level and are available to all nodes (flow agent) or to the single prompt (single-prompt agent). They are ideal for configuration, defaults, and passing caller-specific data.

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Characteristics

  • Scope: Global to the workflow (all nodes in flow agent; entire prompt in single-prompt agent)
  • Where to define: Variables panel at workflow level
  • Default values: Any supported data type
  • Reference syntax: {{variable_name}}
  • Single-prompt agents: Custom variables are exposed as params in the agent configuration

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When to Use

  • Values that change per deployment (e.g. business name, support email)
  • Default messages or responses
  • State or configuration shared across the flow
  • Single-prompt agents: Any data you want to pass into the prompt as parameters

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Example Use Cases

business_name: "Acme Corporation"
support_email: "[email protected]"
max_retry_attempts: 3
is_after_hours: false

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Flow Builder vs Single Prompt Agents

AspectFlow Builder AgentSingle Prompt Agent
AvailableAll nodes, including globalEntire prompt
DefinitionVariables panelVariables panel (stored as params)
Usage{{variable_name}} in node configs{{variable_name}} in prompt; custom vars become params
Conditional logicFlow transitions, router nodes{{#if variable_name}} in prompt (e.g. {{#if enable_transfers}})
In single prompt agents, custom variables are the only user-defined variables; there are no extracted or static variables. See Single Prompt Agent Variables for availability, configuration examples, and when to upgrade to Flow Builder. See Template Syntax & Naming for naming and syntax.