Start here for literature questions. ?q=<question> or ?paper=<DOI or title> -> the matching research communities and sub-communities (with why each matched and its trend) and reading lists in four lenses: relevant, foundational, now, newest. ?page= (1-5), ?page_size= (papers per lens, max 10), ?lenses=. Each page is one call (Personal+ key, or per page via x402).