Transition conditions

Prompt conditions judged by the LLM, equation conditions on dynamic variables, combined conditions, and the operators and comparison rules Tried uses.

Every normal edge has a transition_condition. Tried has three kinds. In the edge editor under Transitions they are the Prompt, Equation and Both options.

UI	`type`	Decided by	Cost
Prompt	`prompt`	The LLM, from a sentence you write	Part of an LLM call
Equation	`equation`	Exact rules on dynamic variables	No LLM call
Both	`equation_prompt`	Equations must hold, then the LLM judges the sentence	LLM call only when the equations hold

Prompt conditions#

{ "type": "prompt", "prompt": "The caller wants to book an appointment" }

Each prompt edge becomes a function the LLM can call, named transition_to_<destination_node_id> (non-alphanumeric characters replaced by _, cut to 64 characters) and described as "Transition when: ". {{variables}} in the condition are rendered.

In a conversation node without an else edge, these functions ride along with the normal reply call: the LLM either answers the caller or calls a transition. In other nodes, a separate LLM call is made with the global prompt, the conversation and the conditions, and the model either calls one transition or answers "none".

Write prompt conditions as a fact about the conversation, from the caller's side:

Weak	Better
Booking	The caller wants to book, move or cancel an appointment
Done	The caller has confirmed their name, date and time
Not interested	The caller says they do not want to continue, or asks not to be called again

If two prompt edges point to the same node, only the first is offered.

Equation conditions#

{
  "type": "equation",
  "equations": [
    { "left": "{{plan}}", "operator": "==", "right": "premium" },
    { "left": "{{age}}", "operator": ">=", "right": "18" }
  ],
  "operator": "&&"
}

Field	Type	Default	Description
`equations`	array, at least 1		Each is `{left, operator, right}`
`equations[].left`	string		A `{{variable}}` template, or a bare variable name
`equations[].operator`	see below
`equations[].right`	string	`""`	A value, or a `{{variable}}` template
`operator`	`"&&"` or `"\|\|"`	`"&&"`	Shown as AND / OR when there are two or more equations

In the editor, click Condition to add an equation and the cross to remove one. The right-hand field is hidden for exists and not_exist.

Operators#

Operator	True when
`==`	Equal. Numbers compare numerically; text compares case-insensitively
`!=`	Not equal
`>`, `>=`, `<`, `<=`	Numeric comparison when both sides are numbers; text comparison otherwise
`contains`	The left text contains the right text (case-insensitive)
`not_contains`	The left text does not contain the right text
`exists`	The variable is set and not empty
`not_exist`	The variable is missing or empty

How values are compared#

Values are strings. A side counts as a number when it parses as one after commas are removed, so 1,200 equals 1200.
Leading and trailing spaces are ignored for ==, != and ordering.
A {{template}} that does not resolve, or resolves to an empty string, counts as missing.
A bare name on the left that is not a known variable counts as missing.
When the left side is missing, every comparison is false except != and not_contains, which are true.

Which variables you can use#

Anything in the call's dynamic variables: agent defaults, request variables (retell_llm_dynamic_variables), contact fields, values saved by extract nodes, response variables from functions, code and MCP nodes, sms_status from SMS nodes, live overrides from update-live-call, and system variables such as current_hour, direction or user_number. See Dynamic variables.

Both (equation and prompt)#

{
  "type": "equation_prompt",
  "equations": [{ "left": "{{plan}}", "operator": "==", "right": "premium" }],
  "operator": "&&",
  "prompt": "The caller asks for a priority callback"
}

The prompt condition is only offered to the LLM when the equations hold. Use it to gate an LLM-judged transition behind a hard rule, for example premium-only routes.

Logic split edges#

Edges on a logic split node are equations in the editor, plus a required Else.

Order matters#

Equations run before prompts and in list order. Put the most specific equation first. Prompt conditions are judged together, so make them mutually exclusive; if two could both apply, the LLM picks one.

Nodes and edgesEdge kinds and evaluation order.Global nodesConditions that apply from every node.Finetune examplesTeach the LLM which transition to take.