medical-codes-mcp-server

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  <h1>@cyanheads/medical-codes-mcp-server</h1>
  <p><b>Decode, search, validate, and crosswalk US medical codes — ICD-10-CM, ICD-10-PCS, HCPCS Level II — over a bundled offline index via MCP. STDIO or Streamable HTTP.</b>
  <div>6 Tools</div>
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[![Version](https://img.shields.io/badge/Version-0.1.3-blue.svg?style=flat-square)](./CHANGELOG.md) [![License](https://img.shields.io/badge/License-Apache%202.0-orange.svg?style=flat-square)](./LICENSE) [![MCP SDK](https://img.shields.io/badge/MCP%20SDK-^1.29.0-green.svg?style=flat-square)](https://modelcontextprotocol.io/) [![npm](https://img.shields.io/npm/v/@cyanheads/medical-codes-mcp-server?style=flat-square&logo=npm&logoColor=white)](https://www.npmjs.com/package/@cyanheads/medical-codes-mcp-server) [![TypeScript](https://img.shields.io/badge/TypeScript-^6.0.3-3178C6.svg?style=flat-square)](https://www.typescriptlang.org/) [![Bun](https://img.shields.io/badge/Bun-v1.3-blueviolet.svg?style=flat-square)](https://bun.sh/)

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[![Install in Claude Desktop](https://img.shields.io/badge/Install_in-Claude_Desktop-D97757?style=for-the-badge&logo=anthropic&logoColor=white)](https://github.com/cyanheads/medical-codes-mcp-server/releases/latest/download/medical-codes-mcp-server.mcpb) [![Install in Cursor](https://cursor.com/deeplink/mcp-install-dark.svg)](https://cursor.com/en/install-mcp?name=medical-codes-mcp-server&config=eyJjb21tYW5kIjoibnB4IiwiYXJncyI6WyIteSIsIkBjeWFuaGVhZHMvbWVkaWNhbC1jb2Rlcy1tY3Atc2VydmVyIl19) [![Install in VS Code](https://img.shields.io/badge/VS_Code-Install_Server-0098FF?style=for-the-badge&logo=visualstudiocode&logoColor=white)](https://vscode.dev/redirect?url=vscode:mcp/install?%7B%22name%22%3A%22medical-codes-mcp-server%22%2C%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40cyanheads/medical-codes-mcp-server%22%5D%7D)

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**Public Hosted Server:** [https://medical-codes.caseyjhand.com/mcp](https://medical-codes.caseyjhand.com/mcp)

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[![Framework](https://img.shields.io/badge/Built%20on-@cyanheads/mcp--ts--core-67E8F9?style=flat-square)](https://www.npmjs.com/package/@cyanheads/mcp-ts-core)

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---

> [!NOTE]
> **Informational, not clinical or coding advice.** This server returns official code descriptions and billable/validity flags from public-domain federal releases to help you decode and look up codes. It is **not** medical advice, and a `valid_billable` result is **not** a coding or reimbursement decision. Always verify codes against the official source releases (CMS, CDC/NCHS, NLM) and your payer's rules before submitting a claim. The bundled data is only as current as the release baked into the build — call `medcode_list_systems` to see exactly which releases are active.

## How it works

The code data is **bundled inside the package** — a single SQLite + FTS5 database (`data/medical-codes.db`) built at package-build time from the canonical federal source files and shipped in the npm tarball and Docker image. The server opens it **read-only** at startup and answers every tool call from disk.

That means the server is **offline, keyless, and deterministic**: no runtime network calls, no API key, no rate limit, single-tenant. The same inputs against the same bundled build always return the same output.

### Bundled code systems

Only freely-redistributable, public-domain US federal code sets are bundled:

| System | Source | Covers |
|:---|:---|:---|
| **ICD-10-CM** | [CDC/NCHS](https://www.cdc.gov/nchs/icd/icd-10-cm/index.html) — US federal, public domain | Diagnoses (billable leaf codes + non-billable category headers) |
| **ICD-10-PCS** | [CMS](https://www.cms.gov/medicare/coding-billing/icd-10-codes) — US federal, public domain | Inpatient procedures (axis-based 7-character codes) |
| **HCPCS Level II** | [CMS](https://www.cms.gov/medicare/coding-billing/healthcare-common-procedure-system) — US federal, public domain | Supplies, drugs, and non-physician services |

**RxNorm** ([NLM](https://www.nlm.nih.gov/research/umls/rxnorm/), public domain) — the drug-crosswalk layer (drug name ↔ RXCUI ↔ NDC, ingredients, brands) — is **not bundled yet**; it lands in a later release. Until then, `medcode_map_codes`' drug directions return a `direction_unavailable` error, and the hierarchy directions (`parents`/`children`) work today.

CPT (AMA copyright) and SNOMED CT / LOINC (UMLS-license-gated) are intentionally absent — they are not freely redistributable, so they cannot ship in an offline package.

**US scope.** ICD-10-CM and ICD-10-PCS are the US clinical modifications, not the WHO ICD-10/ICD-11 base or another country's national modification.

## Tools

Six tools organized goal-first — one per user action, with a `system` discriminator instead of a per-system tool for each of the bundled code sets. All are read-only.

| Tool | Description |
|:---|:---|
| `medcode_get_code` | Decode 1–50 codes to their official descriptions. Auto-detects the system per code; partial-success `found` / `notFound`. |
| `medcode_search_codes` | Full-text search over official descriptions — go from a clinical description to the code. |
| `medcode_check_code` | Validate a code's existence, currency, and billability, with a `whyNot` for non-billable/terminated cases. |
| `medcode_map_codes` | Crosswalk a code within its hierarchy (`parents`/`children`); RxNorm drug directions land in a later release. |
| `medcode_browse_hierarchy` | Walk a system's hierarchy for discovery without a search term. |
| `medcode_list_systems` | List bundled systems with release identifiers, effective dates, and code counts (provenance). |

### `medcode_get_code`

Decode one or more codes seen in a claim, EHR field, or another health server's output. The 80% entry point.

- Accepts 1–50 codes; mixed systems are fine — each code's system is detected independently from its shape
- Partial success: resolved codes in `found`, unresolved in `notFound` with a per-code reason, so one bad code never fails the batch
- An explicit `system` overrides auto-detection when a value is genuinely ambiguous (an ambiguous code lists its `candidateSystems`)
- `includeHierarchy` attaches each code's parent and immediate children
- The resolved `system` is echoed on every result for chaining into `medcode_map_codes` or a billability check

---

### `medcode_search_codes`

Find codes whose official descriptions match a described concept — the reverse of `medcode_get_code`.

- Every search term must appear (prefix-matched), so `"diabetic neuropathy"` returns codes mentioning both
- Filter by `system`, `billableOnly` (exclude headers/categories), and `chapter`
- Ranked by full-text relevance; results echo the resolved system per row
- Discloses truncation when the result hits the cap, and returns an explicit notice (with the parsed query) when nothing matched

---

### `medcode_check_code`

Validate whether a code is safe to submit, before a claim goes out.

- Discriminated status: `valid_billable`, `valid_not_billable`, `valid_header`, or `terminated`
- A `whyNot` string explains the non-billable and terminated cases (e.g. "valid ICD-10-CM category but not billable — submit a more specific child code")
- Validity vs. existence is split: a non-billable or terminated code is a **successful** result with a `whyNot`, not an error — only a code absent from every bundled system raises `unknown_code`

---

### `medcode_map_codes`

Crosswalk a code across systems and within a hierarchy.

- Hierarchy directions (available now): `parents` and `children` walk a code's prefix hierarchy (ICD-10-CM / HCPCS; ICD-10-PCS codes have no prefix parent)
- Drug directions (`name_to_rxcui`, `ndc_to_rxcui`, `rxcui_to_ndc`, `rxcui_to_ingredients`, `rxcui_to_brands`) are RxNorm-backed and return `direction_unavailable` until RxNorm is bundled in a later release
- Every result carries `source` provenance (which system or edge answered) so a chained call uses the right identifier

---

### `medcode_browse_hierarchy`

Orient in an unfamiliar system or enumerate a category's specific codes, without a search term.

- With no `node`: top-level entries (ICD-10-CM categories, HCPCS range buckets, or ICD-10-PCS first-axis values)
- With a `node`: its immediate children
- ICD-10-CM and HCPCS use a prefix hierarchy (a shorter code is the parent of a longer one); ICD-10-PCS is axis-based — each of the 7 characters is an independent axis, so browsing returns valid next-position axis values, not prefix children

## Features

Built on [`@cyanheads/mcp-ts-core`](https://www.npmjs.com/package/@cyanheads/mcp-ts-core):

- Declarative tool definitions — single file per tool, framework handles registration and validation
- Unified error handling — handlers throw, framework catches, classifies, and formats
- Typed per-tool error contracts — capable clients preview failure modes from `tools/list`
- Structured logging with optional OpenTelemetry tracing
- STDIO and Streamable HTTP transports

Domain-specific:

- Bundled SQLite + FTS5 index — offline, keyless, deterministic; no runtime network I/O, no rate limit
- Code-shape auto-detection routes a code to its system; an explicit `system` disambiguates collisions
- Real billable/validity signal from the source releases — the order-file billable flag drives `medcode_check_code`, not a heuristic

Agent-friendly output:

- Provenance on every response — the resolved `system` is echoed for chaining, and `medcode_list_systems` reports exactly which release is baked into the running build
- Graceful partial failure — `medcode_get_code` returns per-code `found` / `notFound` rows instead of failing the batch
- Discriminated output contracts — `medcode_check_code`'s typed status and `medcode_map_codes`' `source` let callers branch on data, not string parsing

## Getting started

This server ships with the code database bundled — there is no API key to obtain and nothing