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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.

npm install
npm run build
npm test

Privacy

This tool runs locally on your machine and is built not to collect, store, or transmit your data — no analytics, no telemetry, no account. All reference data is bundled — no network calls, and nothing leaves your device. Full policy: https://qinisolabs.github.io/privacy.html.

License

Apache-2.0. ICD-10-CM data is U.S. public domain (NCHS/CMS); see NOTICE.