lookup_icd10

Instructions

Implementation Reference

• index.js:120-165 (registration)

  The tool 'lookup_icd10' is registered with the MCP server on line 120 using server.tool(). It is the first tool registered.

  server.tool(
    "lookup_icd10",
    "Search ICD-10-CM codes by diagnosis name or look up a specific code. Returns code, full description, and category. Essential for clinical documentation agents.",
    {
      query: z
        .string()
        .describe("Diagnosis name (e.g. 'major depressive disorder') or ICD-10 code (e.g. 'F33.1')"),
      limit: z
        .number()
        .int()
        .min(1)
        .max(20)
        .default(10)
        .describe("Number of results to return"),
    },
    async ({ query, limit }) => {
      const url = `${ICD_BASE}/search?sf=code,name&terms=${encodeURIComponent(query)}&maxList=${limit}`;
      const data = await apiFetch(url);
  
      // Response: [total, codes[], null, [code, name][]]
      const total = data[0] || 0;
      const entries = data[3] || [];
  
      if (!entries.length) {
        return {
          content: [{
            type: "text",
            text: `No ICD-10-CM codes found for "${query}".`
          }]
        };
      }
  
      const rows = entries.map(([code, name]) => `- **${code}** — ${name}`);
  
      const text = [
        `## ICD-10-CM Results for "${query}"`,
        `Found ${total} total matches, showing ${entries.length}:`,
        "",
        ...rows,
        "",
        "_Source: NIH National Library of Medicine ICD-10-CM API_"
      ].join("\n");
  
      return { content: [{ type: "text", text }] };
    }
  );

• index.js:122-134 (schema)

  The Zod schema defines two input parameters: 'query' (string, diagnosis name or ICD-10 code) and 'limit' (number, 1-20, default 10).

  "Search ICD-10-CM codes by diagnosis name or look up a specific code. Returns code, full description, and category. Essential for clinical documentation agents.",
  {
    query: z
      .string()
      .describe("Diagnosis name (e.g. 'major depressive disorder') or ICD-10 code (e.g. 'F33.1')"),
    limit: z
      .number()
      .int()
      .min(1)
      .max(20)
      .default(10)
      .describe("Number of results to return"),
  },

• index.js:135-165 (handler)

  The handler function fetches from the NIH ICD-10-CM API (clinicaltables.nlm.nih.gov), parses the response, formats results as markdown, and returns them as text content.

    async ({ query, limit }) => {
      const url = `${ICD_BASE}/search?sf=code,name&terms=${encodeURIComponent(query)}&maxList=${limit}`;
      const data = await apiFetch(url);
  
      // Response: [total, codes[], null, [code, name][]]
      const total = data[0] || 0;
      const entries = data[3] || [];
  
      if (!entries.length) {
        return {
          content: [{
            type: "text",
            text: `No ICD-10-CM codes found for "${query}".`
          }]
        };
      }
  
      const rows = entries.map(([code, name]) => `- **${code}** — ${name}`);
  
      const text = [
        `## ICD-10-CM Results for "${query}"`,
        `Found ${total} total matches, showing ${entries.length}:`,
        "",
        ...rows,
        "",
        "_Source: NIH National Library of Medicine ICD-10-CM API_"
      ].join("\n");
  
      return { content: [{ type: "text", text }] };
    }
  );

• index.js:28-34 (helper)

  The apiFetch() utility function used by the handler to make HTTP requests to external APIs.

  async function apiFetch(url) {
    const res = await fetch(url, {
      headers: { "Accept": "application/json" }
    });
    if (!res.ok) throw new Error(`API error ${res.status}: ${url}`);
    return res.json();
  }