Keyword Tool API can be used to either get the search volume data for the provided keywords or generate keyword suggestions. Hence, the API offers 2 services that are called Search Volume and Keyword Suggestions.
Keyword Tool API can be used to get the search volume data for the list of provided keywords and generate keyword suggestions.
You can find detailed description of the various API services over here:
Updated about a year ago
You can only suggest edits to Markdown body content, but not to the API spec.