The closet crab places to the Inner Harbor are LP Steamers in Locust Point (totally wouldn't go there myself), Bo Brooks and Dockside in Canton and Captain James Landing between Fells Point and Canton. LP Steamers IMO is horrible and the other 3 are just "OK".
Bo Brooks Restaurant
2701 Boston St, Baltimore, MD 21201
Captain James Landing
2127 Boston St, Baltimore, MD 21231