All the seeds I purchase come in fully airtight containers, mostly laminated aluminum/plastic film envelopes and/or miniature sealed plastic test tubes. If you further seal these up airtight. light- and water-proof, even just with plastic wrap and/or aluminum foil, that should be all you need in terms of sealing against moisture and air exchange. If seeds are such multiple times well sealed, further use of desiccant is totally unneeded.
In terms of avoiding temperature fluctuations in a refrigerator, just put the container in a back corner and/or bury it under other items. Wherever you store your seeds is probably where you also want to do any longer-term storage of microbial supplements.
Otherwise, I just keep my seeds with their original packing sealed in an opaque glass jar sitting on a shelf in a well temperature-controlled room, wth an air conditioner now always running, and have no problems storing them for up to a year. But yes, refrigeration is best.