Paper Lookup
This skill gives you 11 academic literature APIs with documented endpoints. Your job is to turn the user's intent into a reproducible retrieval: pick the authoritative database(s), make bounded and rate-limited calls, and return an answer with enough provenance (endpoints, parameters, identifiers, access date) that a human or another agent can repeat it.
A literature lookup is only as trustworthy as it is repeatable. Prefer explicit identifiers and documented endpoints over broad guessing, report what you queried, and say plainly when a result is partial or a database came back empty — a silent gap reads as "nothing exists" when it may just mean "not indexed here."
These APIs fail with HTTP 200. That is the recurring hazard across all eleven, and the reason for most of the rules below. PMC eFetch returns a well-formed article with no <body> when the publisher forbids redistribution. arXiv returns totalResults: 1 and one entry titled Error for a malformed parameter, and silently rewrites an unknown field prefix to all:. Europe PMC puts errCode in a 200 body. bioRxiv accepts an out-of-step pagination cursor and returns the wrong 30 records. None of the…
