DOI lookup

Resolve one DOI to its metadata record (title, year, publisher, type, authors, link); found is false when the provider has no record. unpaywall covers Crossref-registered DOIs and adds open-access status, best open-access URL and license; datacite covers DataCite DOIs such as research datasets and software.

Endpoint	POST /v1/doi-lookups
Scope	doi_lookup:lookup
MCP tool	doi_lookup
Usage units	records

Usage units appear in execution.usage.units for reconciliation and billing.

Request fields

Field	Type	Required	Description
invocation_id	string	yes	The market’s invocation id: one execution per id and operation, so a retry with the same id is rejected instead of charged twice. 1-128 characters of A-Z a-z 0-9 . _ : -.
provider	string	yes	Provider that serves the request; choose by the coverage described for this tool. One of: datacite
doi	string	yes	DOI as 10.<registrant>/<suffix>, optionally prefixed by https://doi.org/, https://dx.doi.org/ or doi:, at most 300 characters.

Providers

Provider	Region	Source	Limits
datacite	DE	DataCite, for DataCite-registered DOIs (datasets, software)	timeout_seconds: 30

Example

curl

curl -sS https://services.zgi.im/v1/doi-lookups \
  -H "Authorization: Bearer $ZGI_SERVICES_TOKEN" \
  -H 'Content-Type: application/json' \
  -d '{"invocation_id": "docs-1791778521-doi_lookup", "provider": "datacite", "doi": "10.5438/0012"}'

HTTP

POST /v1/doi-lookups HTTP/1.1
Host: services.zgi.im
Authorization: Bearer <token>
Content-Type: application/json

{
  "invocation_id": "docs-1791778521-doi_lookup",
  "provider": "datacite",
  "doi": "10.5438/0012"
}

MCP

Over MCP, the tool arguments are exactly the HTTP request body.

request.json

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "doi_lookup",
    "arguments": {
      "invocation_id": "docs-1791778521-doi_lookup",
      "provider": "datacite",
      "doi": "10.5438/0012"
    }
  }
}

curl -sS https://services.zgi.im/v1/mcp \
  -H "Authorization: Bearer $ZGI_SERVICES_TOKEN" \
  -H 'Content-Type: application/json' -H 'Accept: application/json, text/event-stream' \
  -H 'MCP-Protocol-Version: 2025-11-25' \
  -d @request.json

Response

A real response, with lists cut to two items and long text shortened.

{
  "code": 0,
  "message": "success",
  "data": {
    "execution": {
      "id": "exe_01a12e52943c77ddb4bd0f2953dfd014",
      "invocation_id": "docs-1791778521-doi_lookup",
      "capability": "doi_lookup",
      "operation": "doi_lookup.lookup",
      "provider": "datacite",
      "outcome": "succeeded",
      "error_category": null,
      "error_code": null,
      "usage": {
        "provider_requests": 1,
        "units": [
          {
            "name": "records",
            "value": 1,
            "source": "measured"
          }
        ]
      },
      "upstream_ref": null,
      "request_id": "req_302c19f0d97515daaa5ff739",
      "started_at": "2026-10-12T04:15:26.268512227Z",
      "finished_at": "2026-10-12T04:15:26.91534647Z",
      "duration_ms": 646
    },
    "result": {
      "found": true,
      "record": {
        "doi": "10.5438/0012",
        "title": "DataCite Metadata Schema Documentation for the Publication and Citation of Research Data v4.0",
        "year": 2016,
        "publisher": "DataCite e.V.",
        "type": "Documentation",
        "authors": [
          "DataCite Metadata Working Group"
        ],
        "url": "https://schema.datacite.org/meta/kernel-4.0/index.html",
        "is_open_access": null,
        "open_access_url": null,
        "license": null,
        "resource_type_general": "Text"
      },
      "source": {
        "name": "DataCite",
        "license": "CC0-1.0",
        "url": "https://datacite.org"
      }
    }
  }
}