  The sensitivity and field of view of the Canadian Hydrogen Intensity Mapping
Experiment (CHIME) has enabled its fast radio burst (FRB) backend to detect
thousands of FRBs. However, the low angular resolution of CHIME prevents it
from localizing most FRBs to their host galaxies. Very long baseline
interferometry (VLBI) can readily provide the subarcsecond resolution needed to
localize many FRBs to their hosts. Thus we developed TONE: an interferometric
array of eight $6~\mathrm{m}$ dishes to serve as a pathfinder for the CHIME/FRB
Outriggers project, which will use wide field of view cylinders to determine
the sky positions for a large sample of FRBs, revealing their positions within
their host galaxies to subarcsecond precision. In the meantime, TONE's
$\sim3333~\mathrm{km}$ baseline with CHIME proves to be an excellent testbed
for the development and characterization of single-pulse VLBI techniques at the
time of discovery. This work describes the TONE instrument, its sensitivity,
and its astrometric precision in single-pulse VLBI. We believe that our
astrometric errors are dominated by uncertainties in the clock measurements
which build up between successive Crab pulsar calibrations which happen every
$\approx 24~\mathrm{h}$; the wider fields of view and higher sensitivity of the
Outriggers will provide opportunities for higher-cadence calibration. At
present, CHIME-TONE localizations of the Crab pulsar yield systematic
localization errors of ${0.1}-{0.2}~\mathrm{arcsec}$ - comparable to the
resolution afforded by state-of-the-art optical instruments ($\sim 0.05
~\mathrm{arcsec}$).
