"""Metadata retrieval tool for academic papers."""
import asyncio
from typing import Any
from ..formatters import format_metadata
from ..scihub_core.core.doi_processor import DOIProcessor
from ..scihub_core.core.year_detector import YearDetector
from ..scihub_core.sources.arxiv_source import ArxivSource
from ..scihub_core.sources.unpaywall_source import UnpaywallSource
from ..server import EMAIL, mcp
@mcp.tool()
async def paper_metadata(identifier: str) -> str:
"""
Get paper metadata without downloading (fast, <1s).
Sources: Unpaywall, Crossref, arXiv APIs
Returns: title, authors, year, journal, OA status, available sources
Args:
identifier: DOI, arXiv ID, or URL
Returns:
JSON with metadata fields
Examples:
paper_metadata("10.1038/nature12373") # DOI
paper_metadata("2301.00001") # arXiv ID
"""
def _get_metadata() -> dict[str, Any]:
"""Synchronous wrapper for metadata retrieval."""
# Normalize the identifier to DOI (also strips whitespace)
doi_processor = DOIProcessor()
doi = doi_processor.normalize_doi(identifier)
metadata: dict[str, Any] = {"doi": doi, "available_sources": []}
available_sources: list[str] = []
# Handle arXiv identifiers directly (skip Crossref/Unpaywall)
arxiv_source = ArxivSource(timeout=10)
if arxiv_source.can_handle(doi):
try:
arxiv_data = arxiv_source.get_metadata(doi)
if arxiv_data:
metadata.update(arxiv_data)
available_sources.append("arXiv")
else:
metadata["error"] = "Metadata not available from arXiv. Please verify the ID."
except Exception as e:
metadata["arxiv_error"] = str(e)
metadata["available_sources"] = available_sources
return metadata
try:
# Try Unpaywall first (primary metadata source)
if EMAIL:
unpaywall = UnpaywallSource(email=EMAIL, timeout=10)
unpaywall_data = unpaywall.get_metadata(doi)
if unpaywall_data:
metadata.update(unpaywall_data)
# Determine available sources
if unpaywall_data.get("is_oa"):
available_sources.append("Unpaywall")
# Always potentially available via Sci-Hub (for pre-2021 papers)
year = unpaywall_data.get("year")
if year and year < 2021:
available_sources.append("Sci-Hub")
except Exception as e:
metadata["unpaywall_error"] = str(e)
# Fallback to Crossref for year if not available
if "year" not in metadata or not metadata["year"]:
try:
year_detector = YearDetector()
year = year_detector.get_year(doi)
if year:
metadata["year"] = year
# Add Sci-Hub as potential source for old papers
if year < 2021 and "Sci-Hub" not in available_sources:
available_sources.append("Sci-Hub")
except Exception as e:
metadata["crossref_error"] = str(e)
# Update metadata with collected sources
metadata["available_sources"] = available_sources
# If no sources found and no year, it might be a very new or invalid DOI
if not available_sources:
metadata["error"] = (
"Metadata not available from Unpaywall or Crossref. "
"Please verify the DOI is correct."
)
return metadata
# Run metadata retrieval in thread pool
metadata = await asyncio.to_thread(_get_metadata)
# Format and return as JSON
return format_metadata(metadata)
