Crossref MCP Server

Instructions

Implementation Reference

• mcp-server.js:199-281 (registration)

  MCP server.tool() registration for 'getWorkByDOI', including description, input schema, and full inline handler implementation that fetches Crossref API and returns formatted JSON.

  server.tool(
    "getWorkByDOI",
    "Retrieve a specific scientific paper by its DOI",
    {
      doi: z.string().describe("The DOI to look up"),
    },
    async ({ doi }) => {
      try {
        // Remove any URL prefix if present
        const cleanDoi = doi.replace(/^https?:\/\/doi.org\//, "");
  
        // Use the direct Crossref API endpoint
        const url = `${CROSSREF_API_BASE}/works/${cleanDoi}`;
        const response = await fetch(url, {
          headers: {
            "User-Agent": "Crossref MCP Server",
          },
        });
  
        if (!response.ok) {
          throw new Error(`API request failed with status ${response.status}`);
        }
  
        const data = await response.json();
        const work = data.message;
  
        if (!work) {
          return {
            content: [
              {
                type: "text",
                text: JSON.stringify(
                  {
                    status: "not_found",
                    query: { doi },
                    message: `No work found with DOI: ${doi}`,
                  },
                  null,
                  2
                ),
              },
            ],
          };
        }
  
        const formattedWork = formatWorkToJson(work);
  
        return {
          content: [
            {
              type: "text",
              text: JSON.stringify(
                {
                  status: "success",
                  query: { doi },
                  result: formattedWork,
                },
                null,
                2
              ),
            },
          ],
        };
      } catch (error) {
        return {
          content: [
            {
              type: "text",
              text: JSON.stringify(
                {
                  status: "error",
                  message: error.message,
                  query: { doi },
                },
                null,
                2
              ),
            },
          ],
        };
      }
    }
  );

• mcp-server.js:202-204 (schema)

  Input schema definition using Zod for the 'doi' parameter.

  {
    doi: z.string().describe("The DOI to look up"),
  },

• mcp-server.js:205-280 (handler)

  The core handler logic for getWorkByDOI: cleans DOI, fetches data from Crossref API, handles not found and errors, formats result with helper, returns standardized MCP text content with JSON.

  async ({ doi }) => {
    try {
      // Remove any URL prefix if present
      const cleanDoi = doi.replace(/^https?:\/\/doi.org\//, "");
  
      // Use the direct Crossref API endpoint
      const url = `${CROSSREF_API_BASE}/works/${cleanDoi}`;
      const response = await fetch(url, {
        headers: {
          "User-Agent": "Crossref MCP Server",
        },
      });
  
      if (!response.ok) {
        throw new Error(`API request failed with status ${response.status}`);
      }
  
      const data = await response.json();
      const work = data.message;
  
      if (!work) {
        return {
          content: [
            {
              type: "text",
              text: JSON.stringify(
                {
                  status: "not_found",
                  query: { doi },
                  message: `No work found with DOI: ${doi}`,
                },
                null,
                2
              ),
            },
          ],
        };
      }
  
      const formattedWork = formatWorkToJson(work);
  
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify(
              {
                status: "success",
                query: { doi },
                result: formattedWork,
              },
              null,
              2
            ),
          },
        ],
      };
    } catch (error) {
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify(
              {
                status: "error",
                message: error.message,
                query: { doi },
              },
              null,
              2
            ),
          },
        ],
      };
    }
  }

• mcp-server-utils.js:2-29 (helper)

  Supporting utility function formatWorkToJson that transforms raw Crossref work data into a clean, structured JSON object with fields like title, authors, published dates, DOI, etc.

  export const formatWorkToJson = (work) => {
    if (!work) return { error: "No data available" };
  
    return {
      title: work.title?.[0] || null,
      authors: work.author
        ? work.author.map((a) => ({
            given: a.given || null,
            family: a.family || null,
            name: `${a.given || ""} ${a.family || ""}`.trim(),
          }))
        : [],
      published: work.published
        ? {
            dateParts: work.published["date-parts"]?.[0] || [],
            dateString: work.published["date-parts"]?.[0]?.join("-") || null,
          }
        : null,
      type: work.type || null,
      doi: work.DOI || null,
      url: work.URL || null,
      container: work["container-title"]?.[0] || null,
      publisher: work.publisher || null,
      issue: work.issue || null,
      volume: work.volume || null,
      abstract: work.abstract || null,
    };
  };