tusd exposes metrics at the /metrics endpoint (example) in the Prometheus Text Format. This allows you to hook up Prometheus or any other compatible service to your tusd instance and let it monitor tusd. Alternatively, there are many parsers and client libraries available for consuming the metrics format directly.
The endpoint contains details about Go's internals, general HTTP numbers and details about tus uploads and tus-specific errors. It can be completely disabled using the -expose-metrics false flag and it's path can be changed using the -metrics-path /my/numbers flag.