This paper reports the design requirements, practical challenges, and a preliminary design for a magnetic resonance imaging (MRI) guided, three degree-of-freedom (DOF) transrectal prostate intervention robot. We show the operational space constraints imposed by patient anatomy when performing transrectal prostate procedures in a magnetic resonance (MR) scanner bore, as determined by analyzing data from 12 patient procedures with a device. We also describe practical challenges arising in designing a compact actuated MR compatible needle placement robot for MRI-guided transrectal needle intervention in the prostate. We present a preliminary design which aims to improve upon previous un-actuated and partially-actuated devices with the addition of an actuated needle insertion module. Such an enhancement enables needle driving to take place inside the MR scanner bore and thereby may reduce the overall procedure time -- thus improving patient comfort and reducing likelyhood of needle targeting errors resulting from patient motion. We show that it is feasible to add such actuation while reducing the footprint of the device in accordance with the anatomical and MR scanner constraints and practical design requirements.