Eu Cellar

What Eu Cellar does

Eu Cellar exposes the Publications Office of the European Union's CELLAR semantic repository to MCP-compatible clients. The repository covers multiple EU publication types, including Official Journal acts, treaties, consolidated texts, Commission proposals, and Court of Justice judgments.

Its tools support two common workflows. Search by words in document titles and receive identifiers, dates, resource types, and EUR-Lex links. Or retrieve structured catalogue information for one work using its CELEX number or CELLAR identifier. The metadata response can include English titles, the document date, whether the work is in force, resource types, EuroVoc concepts with English labels, and authoring bodies.

For less predictable research tasks, the server accepts user-supplied read-only SPARQL. This makes it suitable for questions involving relationships between works, subjects, authors, and resource types that are not covered by a predefined tool.

How it works

The hosted endpoint is available at https://gateway.pipeworx.io/eu-cellar/mcp. Add that URL to an MCP client that supports remote MCP connections. A local npm package, @pipeworx/mcp-eu-cellar, acts as a stdio bridge: the client starts it with npx, and the bridge forwards requests to the same hosted endpoint. The local option still requires network access and has no offline mode.

The underlying data comes from the CELLAR SPARQL service at https://publications.europa.eu/webapi/rdf/sparql, using the Common Data Model graph. Work identifiers returned by the repository use the Publications Office CELLAR resource format.

Setup and configuration

For a hosted connection, configure the MCP URL in the client. For a local connection, use:

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

Anonymous local calls are supported and are limited to 50 calls per day. A free Pipeworx account and PIPEWORX_API_KEY raise the limit to 200 calls per day; the key is sent as a Bearer token. Setting PIPEWORX_META_TOOLS=1 adds shared Pipeworx tools, such as cross-catalog question routing, to the local server's tool list. The hosted pack endpoint already exposes shared gateway tools alongside the Eu Cellar tools.

Tools and capabilities

• cellar_search_works searches titles across resource types, with optional resource type, date range, and result limit parameters.
• cellar_work retrieves a normalized catalogue entry by CELEX number or CELLAR ID.
• cellar_sparql runs a caller-supplied SELECT or ASK query with a result limit. Write operations are rejected and results are capped.
• HTTP callers can invoke tools through the gateway's /v1/tools/ endpoints without using an MCP client.

Limitations and notes

Custom SPARQL requires endpoint-specific conventions. Virtuoso full-text search should use bif:contains; a generic CONTAINS filter can time out on title searches. CELEX values are typed RDF literals, so queries need the appropriate xsd:string type. Titles may be returned with or without language tags, and hand-written queries can produce multiple rows for one work because titles, types, subjects, and authors form a cross-product. The normalized work tool handles that consolidation.

The endpoint expects the format query parameter for reliable response serialization; an Accept header alone may return RDF/XML. Malformed SPARQL can arrive as an HTTP 200 response containing an HTML error page, which the server rejects rather than treating as an empty result. Behind an HTTPS proxy, Node's fetch implementation may require NODE_USE_ENV_PROXY=1.