Add a book to my library

Log reading on the signed-in reader's Siftivo shelves: add a book to want to read (NOT_STARTED), mark it READING, FINISHED or DNF, rate it, or record progress. Suits "add X to my list", "I just finished X, four stars" and "I'm halfway through X". "Finished it, four and a half stars" is one call with readingStatus FINISHED and rating 4.5. The workId comes from search_books. Each field given replaces what the reader had there before, so send a rating or a note only when they asked for that one to change. Omitting readingStatus leaves the book on the shelf it is already on. Needs a linked Siftivo account.

Not callable on this REST surface. It acts on the signed-in reader's own library, and this path answers 401 to every caller regardless of credentials. Reach it over MCP at https://api.siftivo.com/mcp, which runs the OAuth handshake.