The Grimoires are mechanical books powered by clockwork capable of recording voice as both sound and text, and for writing in. They are incapable of recording thought and do not transmit things such as fire, water, or blood (these will not affect others' Grimoires).
Each Grimoire is distinct and different according to each individual and will only open if the appropriate key sequence is used (this can be as simple as flicking a few gears, turning a knob, using a key, etc.) Within them is an infinite supply of paper that can be written on and they are all innately linked to one another so that when one writes something in their Grimoire, everyone else can see it printed in their own.
The Grimoires are not indestructible and can be destroyed or lost, however upon returning to the Clockwork Tower they will find a new tome placed within their room or be presented with one by a Steward. The Grimoires will not follow a character around and must be transported manually.
They also help characters adapt to certain language barriers.