Agent Script Pattern: Using Conditionals

Use conditionals to deterministically control agent behavior based on variable values. Conditionals evaluate before the prompt reaches the LLM.

Why Use This Pattern

Conditionals let you make deterministic decisions about which instructions are included in the prompt, which actions run, or which subagents to transition to. Conditionals don’t rely on LLM interpretation.

Pattern Example: Show Gold members a thank-you message and their points balance, while Platinum VIP members see an exclusive welcome with additional perks.

Conditional Instructions

Customize the prompt based on variable values.

1reasoning:
2  instructions: ->
3    | Refer to the user by name {!@variables.member_name}.
4
5    if @variables.loyalty_tier == "Gold":
6      | Thank the customer for being a Gold member.
7
8    if @variables.loyalty_tier == "Platinum VIP":
9      | Thank the customer for being a Platinum VIP member.

Only the relevant instruction is included in the prompt sent to the LLM.

Prompt sent to LLM if the customer’s name is Jo Richards and they’re a VIP member: Refer to the user by Jo Richards. Thank the customer for being a Platinum VIP member.
Prompt sent to the LLM if the customer’s name is Jane Smith and they’re a Gold member: Refer to the user by Jane Smith. Thank the customer for being a Gold member.

Conditional Actions

Run actions only when specific conditions are met. In this example, the agent only looks up the current order if we don’t have an order summary, improving response time and reducing system usage.

1reasoning:
2  instructions: ->
3    if @variables.order_summary == "":
4      run @actions.lookup_current_order
5        with member_email=@variables.member_email
6        set @variables.order_summary = @outputs.order_summary
7
8    | Show the user their order summary: {!@variables.order_summary}.

Conditional Transitions

Route users to different subagents based on conditions.

1reasoning:
2  instructions: ->
3    if @variables.loyalty_tier == "Platinum VIP":
4      transition to @subagent.vip_support

The transition happens immediately, before the LLM processes any other instructions. See Required Subagent Flow for related patterns.

If/Else Logic

Handle mutually exclusive conditions with if and else logic.

1reasoning:
2  instructions: ->
3    if @variables.order_summary.days_since_order <= 60:
4      set @variables.return_eligibility = True
5      | Offer to process return using {!@actions.create_return}.
6    else:
7      | Politely explain the return period has expired.

Multiple Conditions

Keep in mind that you can combine conditions using and or or.

1reasoning:
2  instructions: ->
3    if @variables.verified == True and @variables.is_business_hours == True:
4      | You can escalate to a live representative if needed.

Tips

Initialize variables for reliable checks: It’s typically a good practice to give variables default values (for example, = "" or = False) so conditional checks work correctly.
Use is None for null checks: Use @variables.value is None to check whether a variable has no value assigned. This check is different from checking for an empty string (@variables.value == ""), for example. The == "" expression checks for an empty string (which is a valid assignment), whereas is None checks for an unassigned value.

Use parentheses to control evaluation order: Use parentheses () to explicitly group the conditionals you want evaluated together. For example, an action could have this available when condition:

1available when @variables.customerType == "Valued" and @variables.QualificationEnabled == True and (@variables.HasSalesInterest == True or @variables.WantsMeeting == True) and @variables.QualificationFlowStep != "COMPLETE"