To access metadata when debugging a device, debug access port circuitry including a debug interface receives commands from a debugger, and a bus interface coupled to a bus enables the debugger to access a memory system of the device. The device operates on data granules having associated metadata items, and the bus interface enables communication of both the data granules and the metadata items over the bus. The debug access port circuitry has storage elements accessible via the commands issued from the debugger, such that the accesses performed within the memory system via the bus interface are controlled in dependence on the storage elements accessed by the commands. A metadata storage element stores metadata items, and the debug access port circuitry is responsive to a command from the debugger to perform a memory direct access to transfer metadata items between the metadata storage element and the memory system.