Does anyone know how to either search content in the Description field or make the message box hold more characters?
You've asked two questions here.
Q 1) How to search content in the Description field
Q 2) How to make the message box hold more characters.
You don't mention with which entity you are working. I am going to assume that you are referring to the fields oppo_description and oppo_note of the opportunity entity.
A 1) The Description field for the opportunity is cover by both the quick find and keyword search features so I don't understand what you mean by searching content in the description field.
A 2) The field oppo_description is the datatype nvarchar and its default length in the database is 100. This creates a max length for this field of 50 characters. Within the Admin screens for the Opportunity entity the field is defined as a Max Length of 50 and a Entry Width of 30. Strings longer than 50 Characters will be truncated.The field oppo_note is the database type nvarchar(max) which allows it to hold The maximum storage size for this type of field is 2^30-1 characters (2 GB)