The phrase "are mostly designed to" is correct and usable in written English.
It can be used to describe the primary purpose or function of something, indicating that it is intended for a specific use or outcome, but not exclusively so.
Example: "These tools are mostly designed to enhance productivity in the workplace."
Alternatives: "are primarily intended to" or "are mainly created to".
Currently, ballistic helmets are mostly designed to stop fragments from diverse explosive devices.
Currently, thermoelectric modules with bulk elements are mostly designed to extract waste heat from solid bodies for power generation.
Previous trials are mostly designed to state the potential mechanisms of the therapeutic effects rather than to detect its whole effect on metabolism.
The immediate proposals on the owners' table, a compilation of ideas presented by the commissioner's office and general managers, are mostly designed to aid low-revenue clubs in their attempt to keep up with their wealthier brethren.
Furthermore, a more localised, targeted approach for diagnosis-assisted treatment of arthritis would be highly beneficial to patients, since state-of-the-art, anti-inflammatory therapies are mostly designed to act systemically, leading to significant, off-target side effects.
The current dual-axis vibratory wheel gyroscopes are mostly designed to have merely one proof mass, so the sensing signal measured from the two axes will interfere with each other and will result in zero rate output.
Joe Levy-Brown The island is mostly designed to accommodate divers but beach bums are also welcome.
Because the oversight system is mostly designed to catch errors, not fraud.
"Doc McStuffins" is mostly designed to entertain, a minus for parents of preschoolers, who typically want educational components (like the way Dora teaches Spanish and problem solving).
This is particularly true in ballet, where lighting is mostly designed to show three-dimensional bodies moving in complex ways through space clearly and unobtrusively without intruding too much on our consciousness.
This seems like another method that's mostly designed to catch stupid terrorists.There's nothing necessarily wrong with that, and it can be useful, but it's not enough.
