In the EF, when I try "Update Model from Database", the property still says "length:500".
To update the type of existing column, you can
1) delete entity from model and re-add it back, this is not ideal when you have navigation properties, :(
2) or use some third party tools, ie dbmltools
The reason why column type did not get updated, is because
Explanation from MSDN
The ADO.NET Entity Data Model Designer (Entity Designer) uses the Update Model Wizard to update an .edmx file from changes made to the database. The Update Model Wizard overwrites the storage model as part of this process. The Update Model Wizard also makes some changes to the conceptual model and mappings, but it only makes these changes when objects are added to the database. For example, new entity types are added to the conceptual model when tables are added to the database, and new properties are added to entity types when columns are added to a table. For details about what changes are made to the .edmx file, see Changes Made to an .edmx File by the Update Model Wizard.
for more info, see stack overflow link