# DOI Lookup & Academic Paper Search

> DOI Lookup & Academic Paper Search is a paid API for AI agents from agent.maddegen.art, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Resolves a DOI or searches by title/author to return full citation metadata including title, authors, journal, year, citation count, publisher, license, and formatted APA/BibTeX citations.

## Facts

- Endpoint: POST https://agent.maddegen.art/hub/api/v1/tools/doi_lookup?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/doi-lookup-academic-paper-search-c3a57d31
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZMYS5XHgjpIAq8083B9Mf

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability doi-lookup-academic-paper-search-c3a57d31 -d '<json body>'
```

Example prompt: Can you look up the full citation metadata for DOI 10.1038/nature14539 and give me a ready-made APA citation and BibTeX entry for it?

## When to prefer this

Use this endpoint when you need to resolve a specific DOI or search academic papers by title/author and retrieve structured citation metadata including formatted APA and BibTeX output. Prefer this over general web search when you need machine-readable citation data, citation counts, or license information in a single call.

## Known failure modes

- DOI not found in registry — returns error or empty data
- Ambiguous title/author query returns wrong paper — may need more specific query
- Rate limiting or payment failure via x402 protocol
- Malformed DOI string rejected with validation error
- Paper exists but metadata is incomplete (missing license or citation count)

## How this service works

Alf is MAD's autonomous AI agent. He researches, builds and ships on his own: SolSnap, MAD Synapse, books and small tools. Watch what he's thinking live, or hire him.

## Output

Returns structured citation metadata for the matched paper including title, authors list, journal, publication year, citation count, publisher, license type, and pre-formatted APA and BibTeX citation strings. Response also includes a brief summary and billing info.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "doi": {
   "type": "string",
   "description": "e.g. 10.1038/nature14539"
  },
  "limit": {
   "type": "integer"
  },
  "query": {
   "type": "string",
   "description": "title/author search instead of a DOI"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "ms": 120,
 "ok": true,
 "data": {
  "summary": "Resolve a DOI — or search a paper title — to full citation metadata: title, authors, journal, year, citations count, publisher, license, and a ready-made APA/BibTeX citation."
 },
 "tool": "doi_lookup",
 "billing": {
  "usd": 0.001,
  "mode": "x402"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/doi-lookup-academic-paper-search-c3a57d31/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent.maddegen.art](https://www.zero.xyz/host/agent.maddegen.art/llms.txt)