Works a DOI Cites: Reference List (OpenCitations Index)

opencitationsindex/references

Lists the works that one DOI cites, as recorded in the OpenCitations Index: for each, the citation id (OCI), the citing and cited works with their DOI, PubMed, OpenAlex and OMID identifiers, the date, the time between the two publications and self-citation flags. Returns at most the first 500 references and reports the total. OpenCitations data (CC0), passed through unmodified and served by Eden Engine; not an official OpenCitations product.

activeper callv1

Price

$0.0026 per call

You pay the price shown. If a call turns out to cost more than its quote, you pay the actual price, capped at twice the quote. No monthly minimum. Top-ups start at $0.50.

Data source

OpenCitations (opencitations.net)

Citation data from the OpenCitations Index (opencitations.net), published under the CC0 public domain waiver. Served by Eden Engine; not an official OpenCitations product.

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Five steps: search, inspect, learn, run, settle. No per-tool setup; your agent reaches this tool through the meta-tools it already has.

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agent

// 1. search: find the tool
omnial_search({ query: "what you need" })

// 2. inspect: price and input schema
omnial_inspect({ tool: "opencitationsindex/references" })

// 3. learn: read the usage guide at runtime
omnial_learn({ tool: "opencitationsindex/references" })

// 4. run: price the exact call first, then run it
omnial_execute({ tool: "opencitationsindex/references", input: { /* see input_schema */ }, dry_run: true })
omnial_execute({ tool: "opencitationsindex/references", input: { /* ... */ } })

// 5. settle: the call is charged when it finishes, nothing to do

Not connected yet? Point your MCP client at https://mcp.eden-engine.com/mcp, then copy a config for your client.

Pricing

Every charge this tool can incur.

Charge	Price
Per call	$0.0026

Updated: Oct 21, 2026

Input and output schemas

Input schema

input_schema.json

{
  "type": "object",
  "required": [
    "doi"
  ],
  "properties": {
    "doi": {
      "type": "string",
      "pattern": "^10\\.[0-9]{4,9}/[^\\s?#]{1,200}$",
      "description": "A DOI without the doi: prefix, for example 10.1186/1756-8722-6-59."
    }
  },
  "additionalProperties": false
}

Output schema

output_schema.json

{
  "type": "object",
  "required": [
    "total",
    "returned",
    "truncated",
    "references"
  ],
  "properties": {
    "total": {
      "type": "integer",
      "description": "How many references OpenCitations returned for the DOI."
    },
    "returned": {
      "type": "integer",
      "description": "How many of them are in `references` (at most 500)."
    },
    "truncated": {
      "type": "boolean",
      "description": "True when `total` is above 500 and `references` holds only the first 500."
    },
    "references": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "oci": {
            "type": "string",
            "description": "The citation's Open Citation Identifier."
          },
          "cited": {
            "type": "string",
            "description": "Space-separated identifiers of the cited work."
          },
          "citing": {
            "type": "string",
            "description": "Space-separated identifiers of the citing work (omid, doi, pmid, openalex)."
          },
          "creation": {
            "type": "string",
            "description": "Date the citation was created (the citing work's publication date), YYYY, YYYY-MM or YYYY-MM-DD."
          },
          "timespan": {
            "type": "string",
            "description": "ISO 8601 duration between the two publication dates, for example P2Y1M11D."
          },
          "author_sc": {
            "type": "string",
            "description": "yes when the two works share an author (author self-citation), else no."
          },
          "journal_sc": {
            "type": "string",
            "description": "yes when citing and cited works share a journal (journal self-citation), else no."
          }
        },
        "additionalProperties": true
      },
      "description": "The references, in the order OpenCitations returns them."
    }
  },
  "additionalProperties": false
}