Toliara is the southern end of the classic RN7 road journey from Antananarivo, Antsirabe, Fianarantsoa, and Isalo. Taxi-brousse trips are long and tiring; private vehicles make the route far more manageable.
The airport has flights to Antananarivo when schedules cooperate. For Anakao, arrange boat transfers or overland-and-boat combinations in town rather than assuming you can improvise easily at the last minute.