Matching IC drive capacitance with MOSFET input capacitance?
When 


the voltage produced by the uC is sufficient
the switching time (resulting from the - limited - drive capability, maybe further limited by a series resistor,  and the effective (!) gate capacitance) is acceptable
there is no danger of 'backdrive' from the switching in the mosfet back to the gate to the uC (this can be a reason to include a gate series resistor)


When you are switching a 20mA LED or a 100mA relais using a TO92 logic-level mosfet I would drive the gate directly without hesitation (but I would check whether the gate voltage is sufficient) . When PWMming 10A motor I would not dream of doing so. In between there is of course a gray area, where careful consideration (and some smoking experiments) might save you a mosfet driver chip.

(edit - add "using a TXB0108 as fast mosfet driver")

The TXB0108 is a wonderful chip, but it drives its outputs in a very special way: a short pulse of relatively low impedance (50..100 ohm), then sustained by a relatively high impedance (4k). I could not find the duration of the pulse in the datasheet. 

Your mosfet must have an low enough effective gate capacitance that it is sufficiently charged by the pulse. As ballpark value you could use the 70pF mentioned in the TXB0108 datahseet (minus PC stray capacitance, etc.). 

The switching delays of the  TXB0108 are up to ~ 10 ns with 15 pF load. This does not make me feel comfortable about reaching 100 ns with 70 pF. 

The allowed voltage on a TXB0108 pin is 0.5 .. 6.5 V: there is margin beyond the supply range, with clamp currents of 50 mA. That might well mean that the chip is reasonably protected from latch-up and other unwanted effects that could be caused by backdriving. But note that this is in the infamous 'absolute maxima' section, NOT in the normal operations.

Management summary: the TXB0108 datasheet does not provide sufficient details, ballpark spec for the mosfet is &lt; 50 pF effective gate capacitance, 100 ns might be achievable, but experiments will be needed to verify the design. Backdriving might not be a problem (specs look much better than an average uC pin), so the series resistor might not be needed, but again: insufficient data.