Yeah it’s a plugin. It has an option to limit the item description, but it’s at 0, meaning it will not be limited.
// Since some feeds may have titles or descriptins in the feed or items that
// are longer then want fits in your HTML page it is possible to trim them
// with the following 4 variables. A values of 0 (ZERO) displays the full
// length.
$limitItemDescriptionLength = 0; // Not limited, in the URL as ItemDescriptionLength=