# SignalDesk AI Crossref Academic Search

> SignalDesk AI Crossref Academic Search is a paid API for AI agents from x402-agent.kariguetoazul.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-12).

Searches the Crossref scholarly database for academic publications matching a text query, returning DOIs, titles, authors, citations, and publisher metadata.

## Facts

- Endpoint: GET https://x402-agent.kariguetoazul.workers.dev/api/research/crossref-search?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signaldesk-ai-crossref-academic-search-87e3bf94
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4Qy-N9SH15wJpzvQ58YCE

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 signaldesk-ai-crossref-academic-search-87e3bf94
```

Example prompt: Search Crossref for the top 5 academic papers on 'transformer architectures in NLP' and give me their titles, authors, DOIs, and how many times each has been cited.

## When to prefer this

Use this endpoint when you need structured scholarly metadata from Crossref — including DOIs, citation counts, authors, and publisher info — for a natural language keyword query. Prefer this over direct Crossref API calls when you need a ready-transformed JSON response with bounded cost per query via x402 micropayment. Best for literature discovery, citation verification, and academic research workflows.

## Known failure modes

- Empty query string or missing required 'q' parameter returns a validation error
- Query exceeding 200 characters is rejected
- Limit parameter outside 1–20 range is rejected
- Crossref upstream API unavailability causes a 502 or timeout
- No results found for highly specific or misspelled queries returns empty results array
- Rate limiting or quota exhaustion from the paid x402 tier

## How this service works

Evidence-backed autonomous AI jobs and paid data tools. Queue/D1/cron run outside the chat; free quotas and bounded execution apply.

## Output

Returns a JSON object with the total number of matching records in Crossref, metadata about the data source (provider, fetch time, expiry, source URL), and an array of result objects each containing DOI, URL, document type, publication year, title, list of authors, citation count, publisher, and optional license information.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "q"
     ],
     "properties": {
      "q": {
       "type": "string",
       "maxLength": 200,
       "minLength": 1,
       "description": "Search query."
      },
      "limit": {
       "type": "integer",
       "maximum": 20,
       "minimum": 1,
       "description": "Results, default 5."
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "total": 3036540,
  "source": {
   "provider": "Crossref metadata",
   "expires_at": "2026-10-02T10:44:49.355Z",
   "fetched_at": "2026-10-02T09:44:49.355Z",
   "source_url": "https://api.crossref.org/works?query=machine%20learning&rows=3",
   "transformed": true
  },
  "results": [
   {
    "doi": "10.1093/oso/9780198828044.003.0003",
    "url": "https://doi.org/10.1093/oso/9780198828044.003.0003",
    "type": "book-chapter",
    "year": 2019,
    "title": "Machine learning with sklearn",
    "authors": [
     {
      "given": "Thomas P.",
      "family": "Trappenberg"
     }
    ],
    "cited_by": 19,
    "publisher": "Oxford University Press"
   },
   {
    "doi": "10.1002/9781119902881",
    "url": "https://doi.org/10.1002/9781119902881",
    "type": "monograph",
    "year": 2022,
    "title": "Optimization and Machine Learning",
    "authors": [],
    "cited_by": 1,
    "licenses": [
     {
      "URL": "http://doi.wiley.com/10.1002/tdm_license_1.1",
      "start": {
       "date-time": "2022-02-25T00:00:00Z",
       "timestamp": 1645747200000,
       "date-parts": [
        [
         2022,
         2,
         25
        ]
       ]
      },
      "delay-in-days": 0,
      "content-version": "tdm"
     }
    ],
    "publisher": "Wiley"
   },
   {
    "doi": "10.1017/cbo9780511804779.017",
    "url": "https://doi.org/10.1017/cbo9780511804779.017",
    "type": "book-chapter",
    "year": 2012,
    "title": "Machine learning",
    "authors": [],
    "cited_by": 1,
    "licenses": [
     {
      "URL": "https://www.cambridge.org/core/terms",
      "start": {
       "date-time": "2012-06-05T00:00:00Z",
       "timestamp": 1338854400000,
       "date-parts": [
        [
         2012,
         6,
         5
        ]
       ]
      },
      "delay-in-days": 0,
      "content-version": "unspecified"
     }
    ],
    "publisher": "Cambridge University Press"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signaldesk-ai-crossref-academic-search-87e3bf94/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-agent.kariguetoazul.workers.dev](https://www.zero.xyz/host/x402-agent.kariguetoazul.workers.dev/llms.txt)