What details do EICAS systems provide?
The EICAS will have the engine instruments and the crew alerting system in one display.  It is a vital instrument because it displays engine parameters, fuel, the crew alert system and other systems information depending on the specific airplane.  

The CAS (crew alerting) functionality of the EICAS replaces the illuminated fault buttons in older airplanes.


YSSYguy CC-BY-SA 3.0

The electronic CAS that is part of an EICAS display is a superset of these old panels and can display a much bigger set of alerts.  The specific alerts that can be shown will cover most error and failure modes the airplane systems can reasonably encounter.  Cautions are yellow in color and will illuminate the master caution and sound an audible chime.  Warnings are red in color and will 
illuminate the master warning and sound the triple chime (and the fire bell for certain conditions).  There may also be advisory messages displayed in another color, e.g. cyan, on the EICAS.


 EMB-145 EICAS.  The CAS is the upper right portion of the display

The messages themselves are terse and not detailed, though detail can be inferred from the pre-defined message text.  Warnings and cautions that are displayed can be addressed with memory immediate action items (memorized checklists) and/or the QRH (quick reference handbook) which defines the procedures for dealing with problems in a verbose checklist flowchart.  The QRH will be indexed by the messages on the CAS so they can be easily found and referenced.