Ask an LLM what an ICD-10-CM code means and it will answer confidently — and often wrongly: the wrong laterality, the wrong severity, the wrong condition entirely, and it will happily invent a description for a code that doesn't exist. icdwise looks the code up in the official U.S. ICD-10-CM code set and returns the real description — or an honest "not found" instead of a guess.

Asked to describe real ICD-10-CM codes, a frontier model with no tools was wrong ~38% of the time — e.g. it called H40.1131 "severe stage, right eye" (it's mild, bilateral) and T63.011A "ingested mushrooms" (it's rattlesnake venom) — and it fabricated a description for a code that doesn't exist. icdwise: the official text, or "not found." Never a guess.

Add it to Claude

Settings → Connectors → Add custom connector, and paste — no login, no key:

https://icdwise.qinisolabs.workers.dev/mcp

Stateless, reads no user data, requires no secrets. Prefer to run it locally over stdio? Add { "command": "npx", "args": ["-y", "icdwise"] } under mcpServers in your client config.

Use it as a library

npm i icdwise

import { lookupIcd10, validateIcd10, searchIcd10 } from "icdwise";

lookupIcd10("E11.9").description;     // "Type 2 diabetes mellitus without complications"
lookupIcd10("H40.1131").description;  // "Primary open-angle glaucoma, bilateral, mild stage"
validateIcd10("E11.99").valid;        // false — well-formed but not a real code
searchIcd10("generalized anxiety");   // → [{ code: "F41.1", description: "Generalized anxiety disorder" }, ...]

Codes are accepted with or without the dot (E11.9 or E119). A well-formed code that isn't in the official set returns found: false with a clear note — it never invents a description.

Tools — 3

Tool	What it answers
lookup_icd10	The official description of a code (+ canonical form and 3-char category)
validate_icd10	Is this a real ICD-10-CM code? (well-formed and in the official set)
search_icd10	Reverse lookup — find the code(s) for a condition by keywords

Data

ICD-10-CM is U.S. public-domain data (NCHS/CMS). The full code set (~74,000 codes) is bundled and generated from the official CMS release via npm run build-data <icd10cm-codes-YYYY.txt> (see scripts/build-data.mjs); every response reports the datasetVersion it used. Descriptions are the official text — the curated, versioned dataset kept current is the moat.

What it is not

Not medical advice, and not a determination of billability, coverage, or clinical appropriateness.
Not ICD-10 (WHO) or ICD-11 — this is ICD-10-CM (the U.S. Clinical Modification).
Not a guesser — unknown/retired/non-leaf codes return an honest "not found", never a fabricated description.

Architecture

A single TypeScript package exposing one MCP server over two transports — stdio (local / npx) and a Cloudflare Worker (hosted edge endpoint) — both driven by the same core.ts tool definitions, which also power the importable library.