@pipeworx/opencitations

OpenCitations MCP — open-license citation index (COCI + Index APIs). Keyless.

Part of Pipeworx — an MCP gateway connecting AI agents to 1867+ live data sources. This is an independent, unofficial integration — not affiliated with, endorsed by, or published by the upstream provider.

Tools

• references(doi) — DOIs cited BY the given DOI

• citations(doi) — DOIs that cite the given DOI

• citation_count(doi) — number of incoming citations for a DOI

• references_count(doi) — number of outgoing references for a DOI

• metadata(dois) — bibliographic metadata for one or more DOIs (comma-sep list, max 50)

• citation(oci) — a single citation by Open Citation Identifier

Related MCP server: OpenAIRE MCP Server

Data source

https://opencitations.net/index/coci/api/v1/ (COCI) and https://opencitations.net/index/api/v1/ (generic Index endpoints).

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "opencitations": {
      "url": "https://gateway.pipeworx.io/opencitations/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/opencitations/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — ask_pipeworx, discover_tools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

This is deliberate, not multiplexing by accident. The meta-tools are what let a scoped connection answer a question this pack does not cover — via ask_pipeworx, which routes across the whole catalog — without you adding a second MCP server. There is currently no way to mount a pack endpoint without them; if the extra schemas cost you more context than the routing is worth, connect to the full gateway once rather than to several pack endpoints.

Or connect to the full Pipeworx gateway to get every pack's tools listed directly, instead of just this one's:

{
  "mcpServers": {
    "pipeworx": {
      "url": "https://gateway.pipeworx.io/mcp"
    }
  }
}

Both URLs reach the same gateway and the same 1867+ data sources. The only difference is which pack's tools are listed directly; ask_pipeworx reaches all of them from either one.

No MCP client? Call it over HTTP

curl -X POST https://gateway.pipeworx.io/v1/tools/opencitations_references \
  -H 'Content-Type: application/json' \
  -d '{"doi":"10.1371/journal.pone.0123456"}'

No account needed for the first calls. Inspect any tool: GET https://gateway.pipeworx.io/v1/tools/opencitations_references. Find one: POST https://gateway.pipeworx.io/v1/tools/search_packs with {"query":"..."}.

Run it from npm

@pipeworx/mcp-opencitations is a local stdio bridge to the Pipeworx gateway: your MCP client starts it with npx, and it forwards every call to the same https://gateway.pipeworx.io/opencitations/mcp endpoint shown above. It needs network access; there is no offline mode.

{
  "mcpServers": {
    "opencitations": {
      "command": "npx",
      "args": ["-y", "@pipeworx/mcp-opencitations"]
    }
  }
}

Without a key it calls anonymously, capped at 50 calls a day. A free account raises that to 200 a day: get a key at https://pipeworx.io/signup and add "env": { "PIPEWORX_API_KEY": "<your key>" } to the server entry. The key is sent as a Bearer token, the same way a hosted connection sends it, so calls are metered and billed exactly as they are there.

It lists only this pack's tools by default. Set PIPEWORX_META_TOOLS=1 to also list ask_pipeworx and the other gateway-wide tools.

Behind an HTTPS proxy: Node's built-in fetch does not read HTTPS_PROXY by default. Newer Node releases honour it when NODE_USE_ENV_PROXY=1 is set; check your Node version's documentation.

Using with ask_pipeworx

Instead of calling tools directly, you can ask questions in plain English — this works on the pack endpoint above as well as on the full gateway:

ask_pipeworx({ question: "your question about Opencitations data" })

The gateway picks the right tool and fills the arguments automatically.

More

• Docs and guides

• pipeworx.io

License

MIT