Structured Outputs Between Nodes

Schemas as contracts

When node B depends on node A, the schema of A's output is a contract. Keep schemas small and specific: enumerations for categories, booleans for flags, numbers for amounts. Avoid free-text fields that later nodes must parse. When you change a schema, check every node that reads it, and version the workflow. Validate unusual values defensively: an enum blocks unknown categories, but a number may still be out of range.

A schema-first design

Write the contract before the prompt.

classifier output:
  category: enum[billing, technical, other]
  urgent:   boolean
  amount:   number | null      # parsed from text, null if absent
  summary:  string (<= 200 chars)

readers:
  route (if/else)        -> category, urgent, amount
  specialist agent       -> summary
  logging / analytics    -> all fields

List the readers of each field

Before changing a field, look up which nodes read it; schema changes are the most common cause of broken workflows.

Quick check: Which field type is safest for a category used in routing?

• Free text
• An enumeration of allowed values
• An image
• A random number