The Agent is designed to use Kernel-based timestamps to measure the Network Performance metrics (latency, jitter and packet loss). With that design, the timestamps are read directly from the network adapters to increase the precision of the measurements.
On Linux OS, the tc command is often used to simulate network degradation such as increased latency, jitter or packet loss. This technic is not working on the Agent measurements because the command affect packets before they leave the physical network adapter. Since the packet are dropped or buffered before the agent record the timestamps, it has no effect on the measurements.
This is why the Linux tc command has no effect on the measurement the Agent will report.