I sometimes use the word "intelligencer" to refer to informants, correspondents, etc. Someone recently asked me where the word came from. I have no idea but my conceptualization came from Swift:
But, because there are many Effects of Folly and Vice among use, whereof some are general, others confined to smaller Numbers, and others again, perhaps to a few Individuals; there is a Society lately established, who at great Expence have erected an Office of Intelligence, from which they are to receive weekly information of all Important Events and Singularities, which this famous Metropolis can furnish. Strict Injunction are given to have the truest Information. In order to which, certain qualified Persons are employ’d to attend upon Duty in their several Posts; some at the Play-House, others in Churches, some at Balls, Assemblies, Coffee-Houses, and Meetings for Quardille; some at the several Courts of Justice, both Spiritual and Temporal; some at the College, some upon my Lord Mayor and Aldermen in their publick Affairs; lastly, some of converse with favourite Chamber-maids, and to frequent those Ale-Houses and Brandy-shops where the Footmen of great Families meeting in a Morning; only the Barracks and Parliament-House are excepted; because we have yet found no enfans perdus bold enough to venture their Persons at either. Out of these and some other Store-Houses, we hope to gather Materials enough to Inform, or Divert, or Correct, or Vex the Town. (pg. 1-3)