npi-providers-mcp-server

Public Hosted Server: https://npi-providers.caseyjhand.com/mcp

Overview

US healthcare provider directory over the NPPES NPI Registry, with plain-language specialty terms resolved offline against a bundled NUCC taxonomy. Search providers by name, organization, location, and specialty; decode NPIs into professional-practice provider records; and resolve or browse the NUCC taxonomy directly. Runs as a stdio process, a local Streamable HTTP server, or the public hosted endpoint above.

Tools

Resources

All resource data is also reachable via tools; the resources are convenience twins for resource-capable clients.

Related MCP server: npi-verify

Capability reference

npi_search_providers tool

• Search by name_search shortcut, explicit first_name / last_name, organization_name, city / state / postal_code, and provider_type (individual / organization); at least one criterion is required and the registry rejects state-only searches. Person names search individuals and organization_name searches organizations, so mixing the two sides (directly or through provider_type) fails before any registry request

• Plain-language specialty resolves through the bundled NUCC taxonomy to the registry's exact description before searching, echoed back via resolvedTaxonomies / appliedTaxonomyDescription; inactive NUCC codes are never resolved. taxonomy_description is an escape hatch for an already-known exact description (mutually exclusive with specialty)

• Trailing-wildcard (*) matching on names, organization, and city requires at least 2 leading characters; postal_code takes 5 or 9 digits, or a 2–9 digit prefix ending in * (98*, 981*)

• Name searches also match former and other names, and the registry sorts by current name; a row matched through one names it in matchedOtherName (an exact first_name alone never marks a row, since the registry also matches first-name variants)

• Each row's city / state / postalCode is the primary practice location. A location search matches practice addresses only, never mailing addresses: a row is returned only when the primary practice location or another practice location matches every requested location field (any other row the registry returns is filtered out, with a notice counting it), and a row kept on another practice location names it in matchedLocation

• limit 1–200 (default 10), skip 0–1000; the registry never reports a true match total, and the response discloses page-size-not-total via truncated / notice. A full page names the next page in nextPage; one search reaches only its first 1200 matches, so the terminal window (skip 1000, limit 200) instead returns continuationPostalCodes — postal_code prefixes to re-run the same search with, deduplicating by NPI. That split cannot go below a 5-digit ZIP or reach practice addresses outside the US, and the notice says so

• Typed error reasons: no_search_criteria, conflicting_specialty, mixed_provider_criteria, unresolved_specialty, invalid_search_field

npi_get_provider tool

• Accepts a single NPI or up to 10; each must be exactly 10 digits, and each is checked against its NPI check digit before any API call

• Returns every taxonomy (with primary flag, license number and state), practice addresses with phone and fax, credential, sex, sole-proprietor flag, enumeration and last-updated dates, secondary identifiers, and FHIR/Direct endpoints (with their descriptions and routing address)

• Only LOCATION (practice) address rows are kept for individual providers, so their mailing address — often a home address — is withheld; organizations keep both LOCATION and MAILING rows

• Four-way partition: found (resolved records), notFound (confirmed absence — deactivated or never enumerated), errored (upstream failure, distinct from absence — retry these), invalid (failed the NPI check digit — never looked up)

• Throws invalid_npi_format when every requested NPI fails the check digit, and none_found only when every NPI looked up is a confirmed absence; an upstream failure on any NPI surfaces as that underlying error instead

npi_lookup_taxonomy tool

• Three modes: resolve (plain-language term → matching codes/descriptions), get (exact code → full entry, including NUCC's notes), browse (walk grouping → classification → specialization, filterable by grouping and NPI section)

• Every entry carries status (active / inactive) and, for an inactive code, the replacedBy code NUCC names; resolve never returns inactive codes, while get and browse still do. A query that matches only inactive codes fails with no_match naming them and their replacements

• Credential abbreviations resolve, dotted or not (rn, R.N., np, pa, crna, lpn, lvn, emt, er). A query made only of generic words, singular or plural (physician, doctors, M.D., specialist, providers), names no specialty, so it fails with no_match and a hint to browse, rather than matching an unrelated word

• resolve / browse cap results at limit (≤50, default 20) and disclose truncated; page past the cap with skip (0–1000, raised by limit each call)

• A resolved entry's specialization (or classification when specialization is absent) is the exact value npi_search_providers.taxonomy_description accepts

• Typed error reasons: no_match, missing_argument

npi://provider/{npi} resource

• Returns the same decoded record as npi_get_provider, for one NPI, as application/json — only LOCATION address rows are kept for individual providers

• npi must be a well-formed 10-digit NPI; invalid_npi_format when it fails the NPI check digit (no registry request), no_record when the registry has none (deactivated or never enumerated)

npi://taxonomy/{code} resource

• Returns the same entry as npi_lookup_taxonomy mode get (NUCC notes, status, and replacedBy included; inactive codes stay readable), as application/json; cached publicly for 24 hours

• code must match ^\d{3}[A-Z0-9]{6}X$; no_match when no entry exists for the code

Features

Built on @cyanheads/mcp-ts-core: stdio and Streamable HTTP transports, pluggable auth (none / jwt / oauth), swappable storage (in-memory, filesystem, Supabase, Cloudflare KV/R2/D1), structured logging with optional OpenTelemetry tracing.

NPI/NPPES-specific:

• Keyless — runs against the public CMS NPPES NPI Registry API (v2.1) with no API key or account

• Bundled NUCC taxonomy — the 883-code Healthcare Provider Taxonomy (v26.1) ships in the image and loads into an in-memory index at startup, so specialty resolution and code lookups work fully offline with no second upstream

• Specialty resolution turns a vague term ("heart doctor") into the precise taxonomy description the registry filters on, and echoes the match back for the agent to verify

• Detects the registry's quirk of returning HTTP 200 with an Errors[] body on validation failure and maps it to typed, recoverable error reasons

Agent-friendly output:

• Provenance on search — the resolved taxonomy and the exact taxonomy_description sent to the registry are echoed back, so agents can see what was actually searched and re-run with a different code

• Honest pagination — the returned count is disclosed as the page size, never a fabricated grand total; a full page names the exact next page, and a broad query that hits the 1200-match reachable ceiling gets the postal-code prefixes that continue it

• Graceful partial failure — npi_get_provider returns per-NPI found / notFound / errored / invalid rows instead of failing the whole batch

Getting started

Public Hosted Instance

A public instance is available at https://npi-providers.caseyjhand.com/mcp — no installation required. Point any MCP client at it via Streamable HTTP, with this client config:

{
  "mcpServers": {
    "npi-providers-mcp-server": {
      "type": "streamable-http",
      "url": "https://npi-providers.caseyjhand.com/mcp"
    }
  }
}

Self-Hosted / Local

Add the following to your MCP client configuration file. No API key is required — the upstream NPPES registry is keyless.

{
  "mcpServers": {
    "npi-providers-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["@cyanheads/npi-providers-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with npx (no Bun required):

{
  "mcpServers": {
    "npi-providers-mcp-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@cyanheads/npi-providers-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "npi-providers-mcp-server": {
      "type": "stdio",
      "command": "docker",
      "args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/npi-providers-mcp-server:latest"]
    }
  }
}

For Streamable HTTP, set the transport and start the server:

MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp

Prerequisites

• Bun v1.4.0 or higher (or Node.js v24+).

• No API key — the NPPES NPI Registry API is public and keyless. The NUCC taxonomy is bundled, so there is no second data source to provision.

Installation

1. Clone the repository:

git clone https://github.com/cyanheads/npi-providers-mcp-server.git

2. Navigate into the directory:

cd npi-providers-mcp-server

3. Install dependencies:

bun install

4. Configure environment (optional):

cp .env.example .env
# edit .env only if you need to override the NPPES base URL or timeout

Configuration

No required variables — the server runs out of the box against the keyless NPPES registry. All variables below are optional overrides.

See .env.example for the full list of optional overrides.

Running the server

Local development

• Build and run:

  # One-time build
  bun run rebuild
  
  # Run the built server
  bun run start:stdio
  # or
  bun run start:http

• Run checks and tests:

  bun run devcheck   # Lint, format, typecheck, security
  bun run test       # Vitest test suite
  bun run lint:mcp   # Validate MCP definitions against spec

Docker

docker build -t npi-providers-mcp-server .
docker run --rm -e MCP_TRANSPORT_TYPE=http -p 3010:3010 npi-providers-mcp-server

The Dockerfile defaults to HTTP transport, stateless session mode, and logs to /var/log/npi-providers-mcp-server. OpenTelemetry peer dependencies are installed by default — build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

Development guide

See CLAUDE.md/AGENTS.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic

• Use ctx.log for request-scoped logging, ctx.state for tenant-scoped storage

• Register new tools and resources in the createApp() arrays

• Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

Data attribution

Provider data from the CMS NPPES NPI Registry (public domain). The bundled specialty codes are the NUCC Health Care Provider Taxonomy, © American Medical Association on behalf of the National Uniform Claim Committee (NUCC), redistributed unmodified beyond formatting under the NUCC permission. See NOTICE.

Contributing

Issues are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

License

Apache-2.0 — see LICENSE for details.