Robotic surgical tools, systems, and methods relating to robotic surgery include a memory mounted on the tool. The memory can perform a number of functions when the tool is loaded on the tool manipulator: (1) providing a signal verifying that the tool is compatible with that particular robotic system; (2) identifying the tool-type to the robotic system so that the robotic system can reconfigure the programming; or (3) indicating tool-specific information, including measured calibration offsets indicating misalignment of the tool drive system, tool life data, or the like. This information may be stored in a read only memory (ROM), or in a nonvolatile memory which can be written to only a single time. Also provided are improved engagement structures for coupling robotic surgical tools with manipulator structures.