Material Design is adding more guidance on color systems and usability, with a new tool to easily design palettes when creating interfaces. The April 2017 guideline update also adds new recommendations for text fields and designing right-to-left icons.
Simplifying the process of creating, sharing, and applying color palettes, the new tool is web-based and features a simple, clickable interface.
When finished customizing, the tool also allows developers to test if text is readable on different-colored backgrounds. Based on Web Content Accessibility Guidelines legibility standards, it will provide suggestions for minimum text opacity.
In addition to expanding usage basics for text fields, there is a new section on text field boxes for increasing user discoverability. Additionally, there are more resources when dealing with Bidirectionality, including guidance on right-to-left (RTL) icons.