July 2025 | Vellum | Documentation

Expression Input Output Type Improvements

July 1st, 2025

We’ve significantly enhanced the expression input dropdown to make it easier to understand and navigate Node output types in Workflows.

Explicit Output Type Display

The expression input dropdown now explicitly shows Node output types in a separate menu, making it much clearer what type of data you’re selecting when building expressions. This helps prevent type mismatches and makes workflow building more intuitive.

Expression input dropdown displaying Node output types in a separate menu — Expression input dropdown showing explicit output types

Structured Outputs Warning

When a Prompt Node has Structured Outputs enabled, the interface now provides clear warnings to help you select the appropriate JSON output. This prevents common configuration errors and guides you toward the correct output type for your use case.

Expression input showing warning indicators for Structured Outputs — Warning indicator for Prompt Nodes with Structured Outputs

Full Keyboard Accessibility

The new interface is fully keyboard accessible with intuitive navigation:

Up and Down arrow keys: Navigate through the main menu items
Left and Right arrow keys: Step in and out of submenus
Enter: Select the highlighted item
Escape: Close the dropdown or exit submenus

Expression input dropdown with keyboard navigation highlighting — Keyboard navigation in expression input dropdown

This update makes building complex Workflows more accessible and reduces the learning curve for new users while providing power users with faster, keyboard-driven navigation options.