paper-lookup

The saved excerpt is a snapshot from when this skill was listed. The external source remains the complete and most current version.

---
name: paper-lookup
description: Searches 18 scholarly APIs for papers, preprints, citations, open-access full text, repository records, and journal OA status, and returns results with reproducible provenance. Covers PubMed, PMC, Europe PMC, bioRxiv, medRxiv, arXiv, OpenAlex, Crossref, Semantic Scholar, CORE, Unpaywall, OpenCitations, PubTator3, Zenodo, Figshare, ROR, BioStudies, and DOAJ. Use when searching for papers, citations, DOI/PMID/arXiv lookups, abstracts, full text, open-access PDFs, preprints, citation graphs, author publications, biomedical entity annotations, deposited records (Zenodo, Figshare, BioStudies), institution ROR IDs, or any scholarly literature query. Triggers on mentions of any supported database or requests like "find papers on X", "look up this DOI", "who cites this paper", or "get me the PDF".
allowed-tools: Read Bash
license: MIT
compatibility: Needs network access and curl. The bundled scripts require Python 3.11+ and use only the standard library. No credentials are required; NCBI_API_KEY, S2_API_KEY, CORE_API_KEY, and OPENALEX_API_KEY raise rate limits or unlock full text where noted.
metadata:
  version: "2.4"
  last-reviewed: "2026-09-30"
  skill-author: "K-Dense Inc."
---

# Paper Lookup

This skill gives you 18 scholarly 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."

Endpoint contracts were reviewed against official documentation on 2026-09-30. Response examples are illustrative shapes or explicitly dated historical captures; counts, prices, availability, and status values are not current lookup results. Selected public smoke calls and offline parser tests do not establish authenticated full-text access.

**These APIs can fail with HTTP 200.** That is the recurring hazard, 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 treats cursors as absolute offsets, so an incorrect step skips records. Figshare `GET /articles?search_for=` ignores the query and still 200s. OpenCitations answers an unknown DOI with `[{"count": "0"}]`. None of these raise, and every one of them produces a confident, wrong answer. Verify the shape of what you got, not just the status code.

## Core Workflow

1. **Define the retrieval contract** — What is the user after? A specific paper by DOI/PMID/arXiv ID? Papers on a topic? An author's publications? A citation graph? An open-access PDF? Full text? Note any constraints that change the answer: date range, field of study, open-access-only, exhaustive list vs. a few top hits. If a constraint that affects correctness is missing (e.g., "recent" with no year, or an author name with many namesakes), ask rather than guess.

2. **Select database(s)** — Use the selection guide below. Route to the primary database for the intent, then add others only when they earn their place: identifier resolution, open-access lookup, or a known coverage gap. Don't fan out across all eighteen just because they're available.

3. **Read the reference file** — Each database has a file in `references/` with endpoints, parameters, example calls, response shapes, and **the specific ways it fails quietly**. Read the relevant file(s) before c