# Paper Search Mcp

> MCP, CLI, Skills for searching and downloading academic papers from multiple sources like arXiv, PubMed, bioRxiv, etc.

- **Type:** MCP server
- **Install:** `agentstack add mcp-openags-paper-search-mcp`
- **Verified:** Pending review
- **Seller:** [openags](https://agentstack.voostack.com/s/openags)
- **Installs:** 0
- **Category:** [Search](https://agentstack.voostack.com/c/search)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [openags](https://github.com/openags)
- **Source:** https://github.com/openags/paper-search-mcp

## Install

```sh
agentstack add mcp-openags-paper-search-mcp
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Paper Search MCP

A Model Context Protocol (MCP) server for searching and downloading academic papers from multiple sources. The project follows a free-first strategy: prioritize open and public data sources, support optional API keys when they improve stability or coverage, and keep source-specific connectors extensible for advanced users.

  
[](https://smithery.ai/server/@openags/paper-search-mcp)

---

## Table of Contents

- [Overview](#overview)
- [Project Principles](#project-principles)
- [Features](#features)
- [Source Strategy](#source-strategy)
- [Sci-Hub Notice](#sci-hub-notice)
- [Installation](#installation)
  - [Claude Code (Skill)](#claude-code-skill--recommended-for-claude-code-users)
  - [Method 1 — Smithery](#method-1--smithery-one-command-recommended-for-claude-desktop)
  - [Method 2 — uvx](#method-2--uvx-no-install-always-latest)
  - [Method 3 — uv](#method-3--uv-persistent-install)
  - [Method 4 — pip](#method-4--pip-standard-python-install)
  - [Method 5 — npx](#method-5--npx-via-smithery-cli-no-local-python-needed)
  - [Method 6 — Docker](#method-6--docker)
  - [Method 7 — Clone & run from source](#method-7--clone--run-from-source-development--recommended-for-macos-local)
  - [Environment Variables](#environment-variables-env-file)
- [Contributing](#contributing)
- [Demo](#demo)
- [Star History](#star-history)
- [License](#license)
- [TODO](#todo)

---

## Overview

`paper-search-mcp` is a Python-based tool for searching and downloading academic papers from various platforms. It provides tools for searching papers, downloading PDFs, and extracting text, making it ideal for researchers and AI-driven workflows. It can be used as an MCP server (for Claude Desktop and other MCP clients) or as a Claude Code skill with a CLI interface.

## Project Principles

- **Free-First**: Public and open sources are the default roadmap. Paid or restricted sources are not the core direction of this project.
- **Optional API Keys**: API keys are supported only when they improve stability, rate limits, or metadata quality. The MCP should still be usable without them whenever possible.
- **LLM-Friendly Retrieval**: Search results should be standardized, deduplicated, and as complete as possible for downstream LLM workflows.
- **Source Transparency**: Different sources have different strengths. The MCP should make those tradeoffs explicit instead of pretending every source supports full-text retrieval.

---

## Features

- **Two-Layer Architecture**:
  - **Layer 1 (Unified Tooling)**: High-level `search_papers` for multi-source concurrent search & deduplication, and `download_with_fallback` relying on publisher open access links with sequential fallbacks.
  - **Layer 2 (Platform Connectors)**: Modular connectors for specific academic platforms (arXiv, PubMed, bioRxiv, Semantic Scholar, etc.) equipped with intelligent DOI extraction via regex text analysis or API fields.
- **Multi-Source Support**: Search and download papers from arXiv, PubMed, bioRxiv, medRxiv, Google Scholar, IACR ePrint Archive, Semantic Scholar, Crossref, OpenAlex, PubMed Central (PMC), CORE, Europe PMC, dblp, OpenAIRE, CiteSeerX, DOAJ, BASE, Zenodo, HAL, SSRN, Unpaywall (DOI lookup), and optional Sci-Hub workflows.
- **Standardized Output**: Papers are returned in a consistent dictionary format via the `Paper` class.
- **Free-First Design**: Open and public sources are prioritized before any optional commercial or restricted integrations.
- **Optional API-Key Enhancement**: Sources like Semantic Scholar can work better with a user-provided API key, but are not intended to force paid usage.
- **Discovery + Retrieval Workflow**: Google Scholar and Crossref can be used for discovery and DOI backfilling, while open repositories and publisher links are used for lawful full-text resolution where available.
- **OA-First Fallback Chain**: `download_with_fallback` now follows source-native download → OpenAIRE/CORE/Europe PMC/PMC discovery → Unpaywall DOI resolution → optional Sci-Hub.
- **MCP Integration**: Compatible with MCP clients for LLM context enhancement.
- **Extensible Design**: Easily add new academic platforms by extending the `academic_platforms` module.

## Source Strategy

The long-term goal is not to depend on a single search engine, but to combine multiple free and public sources with clear roles:

- **Open metadata backbone**: Crossref, OpenAlex, Semantic Scholar, dblp, CiteSeerX, SSRN, Unpaywall (DOI-centric OA metadata).
- **Discipline-specific sources**: arXiv, PubMed, PubMed Central, Europe PMC, IACR.
- **Open-access full-text sources**: arXiv, PMC, CORE, OpenAIRE, DOAJ, BASE, Zenodo, HAL, publisher open-access links.
- **Discovery and DOI recovery**: Google Scholar can be useful for finding titles, versions, and DOI clues when other public metadata sources are incomplete.

Recommended free-first roadmap:

1. Keep current public sources stable.
2. Add OpenAlex as a broad free metadata source.
3. Add PubMed Central and Europe PMC for stronger biomedical full-text access.
4. Add CORE and OpenAIRE for repository-based open-access retrieval.
5. Use Google Scholar mainly as a discovery fallback, not as the primary canonical source.

## Platform Capability Matrix

This matrix reflects **verified live-integration results** from functional and end-to-end regression tests in this repository. Columns show the highest capability level observed under normal conditions.

| Platform | Search | Download | Read | Notes |
|---|---|---|---|---|
| arXiv | ✅ | ✅ | ✅ | Open API; reliable |
| PubMed | ✅ | ❌ | ⚠️ info-only | Open API; reliable |
| bioRxiv | ✅ | ✅ | ✅ | Open API; reliable |
| medRxiv | ✅ | ✅ | ✅ | Open API; reliable |
| Google Scholar | ⚠️ | ❌ | ❌ | Bot-detection active; set `PAPER_SEARCH_MCP_GOOGLE_SCHOLAR_PROXY_URL` |
| IACR | ✅ | ✅ | ✅ | Open API; reliable |
| Semantic Scholar | ✅ | ✅ (OA) | ✅ (OA) | Works without key (rate-limited); key improves limits; key rejection (403) retried automatically without key |
| Crossref | ✅ | ❌ | ⚠️ info-only | Open API; reliable |
| OpenAlex | ✅ | ❌ | ⚠️ info-only | Open API; reliable |
| PMC | ✅ | ✅ (OA only) | ✅ (OA only) | OA PDFs only; direct download may be blocked by some proxy environments |
| CORE | ✅ | ✅ (record-dependent) | ✅ (record-dependent) | Free key recommended; connector retries with backoff and falls back to key-less on 401/403 |
| Europe PMC | ✅ | ✅ (OA) | ✅ (OA) | OA PDFs only; direct download may be blocked by some proxy environments |
| dblp | ✅ | ❌ | ⚠️ info-only | Open API; reliable |
| OpenAIRE | ✅ | ❌ | ❌ | Open API; retries 3× with escalating request profiles on transient 403 |
| CiteSeerX | ⚠️ | ✅ (record-dependent) | ⚠️ | API endpoint intermittently unavailable / redirects to web archive |
| DOAJ | ✅ | ⚠️ (URL-dependent) | ⚠️ (URL-dependent) | PDF availability varies by article; free key raises rate limits |
| BASE | ⚠️ | ✅ (record-dependent) | ✅ (record-dependent) | OAI-PMH endpoint requires institutional IP registration; returns empty gracefully otherwise |
| Zenodo | ✅ | ✅ (record-dependent) | ✅ (record-dependent) | Open API; reliable |
| HAL | ✅ | ✅ (record-dependent) | ✅ (record-dependent) | Open API; reliable |
| SSRN | ⚠️ | ⚠️ best-effort | ⚠️ best-effort | 403 bot-detection active; public PDF only |
| Unpaywall | ✅ (DOI lookup) | ❌ | ❌ | **Requires** `PAPER_SEARCH_MCP_UNPAYWALL_EMAIL` |
| Sci-Hub (optional) | ⚠️ fallback-only | ✅ | ❌ | Optional; unstable mirrors; user responsibility |
| **IEEE Xplore** 🔑 | 🚧 skeleton | 🚧 skeleton | 🚧 skeleton | Requires `PAPER_SEARCH_MCP_IEEE_API_KEY` to activate |
| **ACM DL** 🔑 | 🚧 skeleton | 🚧 skeleton | 🚧 skeleton | Requires `PAPER_SEARCH_MCP_ACM_API_KEY` to activate |

> ✅ = reliable in live tests.  ⚠️ = works but subject to upstream instability or access restrictions.  ❌ = not supported.  🔑 = key required.  🚧 = skeleton only.

---

## Credential & API Key Requirements

All keys are **optional** unless noted. Configure them in `.env` (preferred) or as shell exports.

| Environment Variable | Provider | Required? | How to obtain |
|---|---|---|---|
| `PAPER_SEARCH_MCP_UNPAYWALL_EMAIL` | Unpaywall | **Yes** (Unpaywall disabled without it) | Any valid email; register at [unpaywall.org](https://unpaywall.org/products/api) |
| `PAPER_SEARCH_MCP_CORE_API_KEY` | CORE | Recommended | Free at [core.ac.uk/services/api](https://core.ac.uk/services/api) |
| `PAPER_SEARCH_MCP_SEMANTIC_SCHOLAR_API_KEY` | Semantic Scholar | Optional | Free at [semanticscholar.org](https://www.semanticscholar.org/product/api) — improves rate limits |
| `PAPER_SEARCH_MCP_GOOGLE_SCHOLAR_PROXY_URL` | Google Scholar | Optional | Your HTTP/HTTPS proxy URL — bypasses bot-detection |
| `PAPER_SEARCH_MCP_DOAJ_API_KEY` | DOAJ | Optional | Free at [doaj.org](https://doaj.org/apply-for-api-key/) — raises hourly rate limit |
| `PAPER_SEARCH_MCP_ZENODO_ACCESS_TOKEN` | Zenodo | Optional | Free at [zenodo.org](https://zenodo.org/account/settings/applications/) — required for private records |
| `PAPER_SEARCH_MCP_IEEE_API_KEY` | IEEE Xplore | **Required to activate** | Free at [developer.ieee.org](https://developer.ieee.org/) |
| `PAPER_SEARCH_MCP_ACM_API_KEY` | ACM DL | **Required to activate** | See [libraries.acm.org/digital-library/acm-open](https://libraries.acm.org/digital-library/acm-open) |

All variables follow the `PAPER_SEARCH_MCP_` prefix scheme. Legacy names without the prefix (e.g. `CORE_API_KEY`, `UNPAYWALL_EMAIL`) are still supported for backward compatibility.

---

## Known Upstream Limitations

Some search failures are caused by external provider instability, not by bugs in this project:

| Source | Symptom | Cause | Workaround |
|---|---|---|---|
| Google Scholar | Returns 0 results / empty HTML | Bot-detection (CAPTCHA) | Set `PAPER_SEARCH_MCP_GOOGLE_SCHOLAR_PROXY_URL` to a proxy |
| Semantic Scholar | 429 rate-limited responses | Anonymous access rate limit | Set `PAPER_SEARCH_MCP_SEMANTIC_SCHOLAR_API_KEY`; if key is rejected (403) connector automatically retries without key |
| CORE | 500 / timeout errors | Unauthenticated rate limiting | Set `PAPER_SEARCH_MCP_CORE_API_KEY` (free); connector retries with exponential backoff and falls back to key-less on 401/403 |
| OpenAIRE | Transient 403 responses | IP-based session rate limiting | Connector retries 3× per profile, escalating: plain session → XML Accept header → raw `requests.get` with Mozilla UA |
| CiteSeerX | 404 via web archive redirect | PSU endpoint intermittently redirects to archive | No workaround; connector returns empty gracefully |
| BASE | Search returns 0 results | OAI-PMH endpoint requires institutional IP registration | Register at [base-search.net](https://www.base-search.net/about/en/) for API access; connector returns empty gracefully otherwise |
| SSRN | HTTP 403 | Bot-detection (Cloudflare) | No workaround; connector tries two endpoints and returns a clear message on failure |
| PMC / Europe PMC | PDF download ProxyError | Local proxy blocking direct HTTPS PDF download | Disable proxy or use `download_with_fallback` instead |
| Unpaywall | Skipped entirely | `UNPAYWALL_EMAIL` env var not set | Set `PAPER_SEARCH_MCP_UNPAYWALL_EMAIL` in `.env` |

## Optional Paid Platform Connectors (Phase 3)

IEEE Xplore and ACM Digital Library connectors are included as **opt-in skeletons**.
They are **disabled by default** — no API calls are made unless you explicitly configure the corresponding keys.

| Platform | Env Var | Status |
|---|---|---|
| IEEE Xplore | `PAPER_SEARCH_MCP_IEEE_API_KEY` | 🚧 skeleton — search registered, download/read raise `NotImplementedError` |
| ACM Digital Library | `PAPER_SEARCH_MCP_ACM_API_KEY` | 🚧 skeleton — search registered, download/read raise `NotImplementedError` |

**How to enable:**

```bash
export PAPER_SEARCH_MCP_IEEE_API_KEY=       # free key at https://developer.ieee.org/
export PAPER_SEARCH_MCP_ACM_API_KEY=         # see https://libraries.acm.org/digital-library
```

Once a key is set, the corresponding source is automatically added to `ALL_SOURCES` and its MCP tools (`search_ieee` / `search_acm`, `download_ieee` / `download_acm`, `read_ieee_paper` / `read_acm_paper`) are registered at server startup.

Without a key the connectors log a startup warning only — the rest of the server is unaffected.

## Free Source Expansion (Phase 4)

Three additional free-source connectors are now integrated into the MCP server:

- `zenodo`: Official Zenodo REST API connector (search + record-dependent PDF/read support).
- `hal`: HAL public API connector (search + record-dependent PDF/read support).
- `ssrn`: Discovery-first connector with hardened parser and best-effort download/read when a direct public PDF link is available.
- `unpaywall`: DOI-centric OA metadata source for standalone lookup (`search_unpaywall`) and fallback URL resolution.

SSRN integration remains compliance-first: it only attempts direct public PDF links exposed by SSRN pages. If login/restricted delivery is required, the connector returns a clear message instead of bypassing access controls.

## Sci-Hub Notice

Sci-Hub support can remain available as an optional connector for users who explicitly choose to enable it, but it should not be treated as the default or recommended full-text path.

- Availability is unstable and mirrors change frequently.
- Legal and policy risks vary by jurisdiction.
- README and tool descriptions should clearly state that users are responsible for enabling and using it.
- Open-access and publisher-permitted sources should be tried first whenever possible.

---

## Installation

Choose the method that best fits your workflow. All methods support the same [optional API keys](#credential--api-key-requirements).

---

### Claude Code (Skill) — recommended for Claude Code users

Install as a Claude Code skill instead of an MCP server. This gives Claude automatic access to paper search when you mention finding papers, academic literature, etc. — no MCP configuration needed.

**Prerequisites**: [uv](https://docs.astral.sh/uv/getting-started/installation/) and [Claude Code](https://docs.anthropic.com/en/docs/claude-code/overview).

**Step 1 — Clone the repo:**

```bash
git clone https://github.com/openags/paper-search-mcp.git ~/paper-search-mcp
```

**Step 2 — Install the skill:**

```bash
mkdir -p ~/.claude/skills/paper-search
cp ~/paper-search-mcp/claude-code/SKILL.md ~/.claude/skills/paper-search/SKILL.md
```

**Step 3 — Update the repo path in the skill:**

Edit `~/.claude/skills/paper-search/SKILL.md` and replace every `` with the absolute path to your clone (e.g. `/Users/yourname/paper-search-mcp`).

**Step 4 (optional) — Configure API keys:**

Create a `.env` file in the repo root for optional API keys (see [Environment Variables](#environment-variables-env-file)).

**That's it.** Next time you start Claude Code, just ask it to find papers — the skill activates automatically. For example:

- "Find me recent papers on CRISPR base editing"
- "Search arxiv and semantic scholar for transformer attention mechanisms"
- "Download the PDF for arxiv paper 2106.12345"

The skill uses a CLI (`paper-search`) that wraps the same library as the MCP server, outputting JSON for search/download and plain text for read.

---

> **MCP Server Config file locations** (for methods below)
> - **macOS**: `~/Library/Application Support/Claude/claude_desktop_config.json`
> - **Windows**: `%APPDATA%\Claude\claude_desktop_config.json`
> - **Linux**: `~/.config/Claude/claude_desktop_config.json`

---

### Method 1 — Smithery (one-command, recommended for Claude Desktop)

```bash
npx -y @smithery/cli install @openags/paper-search-mcp --client claude
```

Smithery automatically writes the correct config block for you. No manual JSON editing needed.

---

### Method 2 — `uvx` (no install, always latest)

`uvx` runs the package directly from PyPI without a permanent install. Requires [uv](https://docs.astral.sh/uv/getting-started/installation/).

```bash
# Install

…

## Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [openags](https://github.com/openags)
- **Source:** [openags/paper-search-mcp](https://github.com/openags/paper-search-mcp)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** yes
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** yes
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: flagged — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/mcp-openags-paper-search-mcp
- Seller: https://agentstack.voostack.com/s/openags
- Browse the marketplace: https://agentstack.voostack.com/browse

---
Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.