From Place-names of Lewis and Harris by Donald Maciver:
Valasaigh : saigh is island sound ; mol, gen. malar, aspirated, mhalar, beach

Valasay lies at the southern end of Tob Valasay. Although part of the settlement of Tobson, it has a separate identity. It is a tiny village with houses on both sides of a footbridge built in the first decade of the 20th century. To live on the west side of this bridge entails carrying all one's needs across.

Tob Valasay, a narrow inlet of the sea, is a special conservation area;  due to its  high salinity it has some very rare marine creatures and seaweed.

Families in Valasay/Tobson lived at the following crofts:
22: Macaulay
23 and 24: Macdonald