1. A method of adding terms from a related document to a document description for a target document, the method comprising: determining that a term found in the related document does not match a filter criteria, wherein terms that match the filter criteria are not added to a document description for the target document, wherein the document description for the target document comprises terms within a plurality of signal streams that are associated with the target document, wherein the related document is related because the target document comprises hyperlinks to the related document; calculating a similarity score for the term, wherein the similarity score is based on cosine similarity between terms of the target document and terms of the related document; calculating a corroboration score for the term based on similarity between terms used in hyperlinks to the related document and the term; calculating a uniqueness score for the term based on whether the term is currently associated with the document description through other signal streams of the plurality of signal streams; calculating a term score for the term based on the similarity score, the corroboration score, and the uniqueness score; and associating the term with the document description because the term score is above a threshold score.