An air/gas-driven tool with an integrated air/gas dryness indicator. The tool includes a housing that defines a cavity. An air/gas dryness detector is disposed in the cavity. An air/gas flow passage is situated to provide a stream of compressed air/gas to the dryness detector. A visual indicator is adapted to provide an indication of compressed air/gas dryness detected by the dryness detector. The tool can be constructed so that the air/gas dryness indicator is provided by way of a removable indicator cartridge containing a dryness-indicating material such as a color changing desiccant or moisture sensitive paper. The indicator cartridge can be sized and configured to be received in a cavity formed in a housing of the air/gas-driven tool, so as to be viewable through a view port formed in the tool. Alternatively, the indicator cartridge can be configured with its own view port and mounted on a surface of the tool while being partially received in the cavity. The air/gas dryness indicator can also be provided with an electromechanical dryness detector and a numeric display that displays relative humidity, dew point temperature, or both.