niggling (adj.)

• advertent
• agog
• alert
• annoying
• assiduous
• attentive
• aware
• captious
• careful
• concentrated
• conscious
• critical
• cynical
• diligent
• earnest
• faultfinding
• finical
• finicky
• frivolous
• fussy
• hairsplitting
• heedful
• hit
• hypercritical
• inconsequential
• insignificant
• intense
• intent
• irksome
• irritating
• jerkwater
• knock
• measly
• meticulous
• mindful
• nagging
• nice
• nit
• nugatory
• observant
• observing
• one-horse
• open-eyed
• openmouthed
• overcritical
• paltry
• peanut
• pestering
• petty
• picayune
• piddling
• piffling
• poky
• punk
• puny
• regardful
• small-time
• trifling
• trivial
• troublesome
• unimportant
• vexatious
• vexing
• watchful
• worrisome
• worrying