scholar-mcp

Multi-source academic paper search, citation graph exploration, and PDF download as an MCP server. Designed for LLM agents doing research.

Fuses results from 9 academic sources via Reciprocal Rank Fusion, with PDF access across 10+ preprint servers.

Quick Start

Claude Code:

claude mcp add scholar -- uvx scholar-mcp

With API key (recommended, higher rate limits):

claude mcp add scholar -e S2_API_KEY=your_key -- uvx scholar-mcp

Claude Desktop (add to config):

{
  "mcpServers": {
    "scholar": {
      "command": "uvx",
      "args": ["scholar-mcp"]
    }
  }
}

Requires Python 3.10+ and uv. No API key needed for basic use.

Tools

Tool	Description
search_papers	Multi-source search with RRF fusion. Filters: year, venue, field, citations, open access
get_paper	Paper details by S2 ID, DOI, ArXiv ID, PMID, or OpenAlex ID
get_citations	Papers citing a given paper (impact-sorted)
get_references	Papers referenced by a given paper
recommend_papers	Similar papers via SPECTER2 embeddings
search_authors	Researchers with h-index, affiliations, paper counts
build_paper_graph	Citation graph with PageRank analytics and Mermaid visualization
search_openreview	Conference papers (ICLR, NeurIPS, ICML)
discover_field	Auto-map a research field: find surveys, foundations, recent trends, build citation graph
save_papers	Save papers to a persistent collection for later reference
list_saved_papers	List or search saved paper collections (persists across sessions)
download_paper	Smart PDF download across 10+ sources
read_paper	Download + extract text from PDF

Search Sources

Source	Coverage	Strength
Semantic Scholar	214M papers	SPECTER2 semantic search
OpenAlex	250M works	Best coverage, impact-ranked citations
arXiv	CS/Math/Physics	Preprints
PubMed	36M biomedical	Medicine, biology
Europe PMC	Biomedical + EU	PubMed superset
Crossref	150M DOIs	Metadata
DBLP	CS bibliography	Conferences, proceedings
INSPIRE-HEP	High-energy physics	Particle physics
CORE	250M open access	Institutional repositories

PDF Download Chain

1. Semantic Scholar open access
2. arXiv direct
3. CORE (institutional repositories)
4. Preprint servers: bioRxiv, medRxiv, SSRN, ChemRxiv, PsyArXiv, EarthArXiv, SocArXiv, engrXiv, AgriXiv, SportRxiv, Preprints.org
5. Unpaywall (legal OA discovery)
6. PubMed Central
7. Sci-Hub (opt-in via SCIHUB_ENABLED=1)

Citation Graph

build_paper_graph builds an interactive citation network:

• BFS expansion with velocity-weighted priority (new + influential papers first)
• PageRank and betweenness centrality via networkx
• Pivot/bridge paper detection
• Topic filtering to keep graph focused
• Mermaid output with color-coded nodes (seed, high-cite, bridge)

build_paper_graph("Attention Is All You Need", max_hops=2, max_papers=20, topic_filter="attention transformer")

Configuration

Variable	Default	Description
S2_API_KEY	-	Semantic Scholar API key (1 req/s)
CORE_API_KEY	-	CORE API key
OPENALEX_EMAIL	-	Email for Unpaywall + OpenAlex polite pool
SCHOLAR_DOWNLOAD_DIR	./downloads	PDF save directory
SCIHUB_ENABLED	false	Enable Sci-Hub as last-resort source

Development

git clone https://github.com/Liyux3/scholar-mcp.git
cd scholar-mcp
uv venv && uv pip install -e ".[dev]"
uv run pytest tests/                          # 42 unit tests
S2_API_KEY=... uv run python tests/smoke_test.py  # quick integration check

42 tests: relevance scoring (26), graph analytics (9), knowledge base (7).

License

MIT