The Rats mod sounds like an iffy one to add to your game on the surface because it, very simply, introduces an invasive species to the game. It adds rat mobs that will break through your wooden structures and eat your food or at the very least contaminate it.
But the real benefit of this mod is what you can do when you tame the rats and create a miniature army to do your bidding! You can protect your home by placing traps, replacing wood walls with stone, and even ocelots will chase them away.
But you can tame them with cheese to get all the benefits of this mod. It may take some time since they are typically skittish of players but just keep trying and eventually they will come around.
Once tamed you can set the rats to tasks by right-clicking them. A GUI will pop up and allow you to change options like wandering or following you to hunting prey and gathering items for you!
Rats can be put in cages for breeding and you can even sneak and right-click tamed rats to sit on your head or shoulders for easy transport!
You can also set a deposit location for the rats to drop their gathered items as well by crafting a cheese staff and right-clicking the location you want.
There are even armor options like hats and upgrades like greater health or attack damage. Or you can go the extreme route and apply a dragon upgrade to make your rat fly and breathe fire. Truly a medieval way to hunt fish in Minecraft.
And this is simply the tip of the iceberg with this mod. Check the wiki here for further information like all upgrade options as well as other tasks rats can do for you. Oh and be careful since there is a chance of introducing the plague to your world with these rats.
This mod also requires an additional API found here.DownloadForumInstall Guide
The plague part is a bit unsettling