  The schema.org initiative led by the four major search engines curates a
vocabulary for describing web content. The number of semantic annotations on
the web are increasing, mostly due to the industrial incentives provided by
those search engines. The annotations are not only consumed by search engines,
but also by other automated agents like intelligent personal assistants (IPAs).
However, only annotating data is not enough for automated agents to reach their
full potential. Web APIs should be also annotated for automating service
consumption, so the IPAs can complete tasks like booking a hotel room or buying
a ticket for an event on the fly. Although there has been a vast amount of
effort in the semantic web services field, the approaches did not gain too much
adoption outside of academia, mainly due to lack of concrete incentives and
steep learning curves. In this paper, we suggest a lightweight, bottom-up
approach based on schema.org actions to annotate Web APIs. We analyse
schema.org vocabulary in the scope of lightweight semantic web services
literature and propose extensions where necessary. We show that schema.org
actions could be a suitable vocabulary for Web API description. We demonstrate
our work by annotating existing Web APIs of accommodation service providers.
Additionally, we briefly demonstrate how these APIs can be used dynamically,
for example, by a dialogue system.
