@fhirfly-io/mcp-server

MCP (Model Context Protocol) server for connecting Claude Desktop to FHIRfly healthcare reference data APIs.

What is this?

This package lets Claude Desktop look up real healthcare reference data including:

NDC - Drug products and packages (FDA)
NPI - Healthcare provider identifiers (CMS)
RxNorm - Drug terminology (NLM)
LOINC - Laboratory codes (Regenstrief Institute)
ICD-10 - Diagnosis and procedure codes (CMS)
CVX/MVX - Vaccine codes (CDC)
FDA Drug Labels - Prescribing information
SNOMED CT - Clinical concepts (IPS free set)
HCC - CMS Hierarchical Condition Category risk adjustment mappings
OPCS-4 - UK NHS procedure classification codes
dm+d - UK Dictionary of Medicines and Devices (NHS)
UCUM - Unified Code for Units of Measure (NLM)
RxClass - Drug classification hierarchy (NLM)
HCPCS - Level II procedure and supply codes (CMS)
MS-DRG - Diagnosis Related Groups for inpatient payment (CMS)
POS - Place of Service codes for claims submission (CMS)
J-Code/NDC Crosswalk - Bidirectional HCPCS J-code to NDC mapping (CMS)
DDI Reference — Drug-drug interaction text from FDA labels + RxNorm enrichment
Connectivity - Provider FHIR endpoints and Direct addresses
SMA - State Medicaid Agency FHIR endpoint directory (CMS)
Claims Intelligence - NCCI edits, MUE limits, PFS/RVU data, coverage determinations

When you ask Claude about medications, providers, or clinical codes, it can look up accurate, current information instead of relying on training data.

Prerequisites

Claude Desktop - Download from claude.ai/download
Node.js 18+ - Download from nodejs.org
FHIRfly API Key - Get one at fhirfly.io (free tier available)

Quick Setup

Step 1: Get a FHIRfly API Key

Go to fhirfly.io and sign up
Navigate to Dashboard > Credentials
Click Create Credential and select MCP (Claude Desktop)
Copy your API key (starts with ffly_)

Step 2: Configure Claude Desktop

Find your Claude Desktop config file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

Add the FHIRfly server configuration:

config.json

{
  "mcpServers": {
    "fhirfly": {
      "command": "npx",
      "args": ["-y", "@fhirfly-io/mcp-server"],
      "env": {
        "FHIRFLY_API_KEY": "ffly_live_your_key_here"
      }
    }
  }
}

Replace ffly_live_your_key_here with your actual API key.

Step 3: Restart Claude Desktop

Completely quit Claude Desktop and reopen it. The FHIRfly tools should now be available.

Verify It Works

Try asking Claude:

"What is NDC 0069-0151-01?"
"Look up NPI 1234567893"
"Search for COVID vaccines in the CVX database"
"What are the drug interactions for Lipitor?"
"Which states have implemented Medicaid FHIR endpoints?"
"Show me the FHIR endpoint details for California's Medicaid program"
"What is the UCUM code for milligrams per deciliter?"
"Convert 100 mg to grams"
"What drugs are in the HMG-CoA Reductase Inhibitors class?"
"Check interactions between aspirin and warfarin"

Claude should use the FHIRfly tools to look up real data.

Available Tools

Tool	Description
`ndc_get`	Look up drug by NDC code
`ndc_search`	Search drugs by name, ingredient, etc.
`npi_get`	Look up provider by NPI number
`npi_search`	Search providers by name, specialty, location
`rxnorm_get`	Look up drug by RxCUI
`rxnorm_search`	Search drug terminology
`loinc_get`	Look up lab test by LOINC code
`loinc_search`	Search lab codes
`icd10_get`	Look up diagnosis/procedure code
`icd10_search`	Search ICD-10 codes
`cvx_get`	Look up vaccine by CVX code
`cvx_search`	Search vaccine codes
`mvx_get`	Look up vaccine manufacturer
`mvx_search`	Search manufacturers
`fda_label_lookup`	Look up FDA drug label
`fda_label_search`	Search drug labels
`fda_label_safety`	Get safety info (boxed warnings, contraindications)
`fda_label_interactions`	Get drug interaction info
`fda_label_dosing`	Get dosing information
`fda_label_sections`	Get specific label sections
`snomed_get`	Look up clinical concept by SNOMED CT ID
`snomed_search`	Search SNOMED CT IPS concepts
`snomed_mappings`	Find cross-terminology mappings for a SNOMED concept
`npi_connectivity`	Look up provider connectivity (FHIR endpoints)
`sma_list_states`	List states with Medicaid FHIR endpoint status
`sma_get_state`	Get SMA FHIR endpoint details for a state
`sma_stats`	Get aggregate SMA implementation statistics
`ncci_validate`	Check if two codes can be billed together (NCCI)
`mue_lookup`	Look up max units of service (MUE limits)
`pfs_lookup`	Look up Medicare fee schedule / RVU data
`coverage_check`	Check LCD/NCD coverage determinations
HCPCS / MS-DRG / POS / J-Code Tools
`hcpcs_get`	Look up an HCPCS Level II procedure/supply code
`hcpcs_modifier_get`	Look up an HCPCS modifier code
`hcpcs_search`	Search HCPCS Level II codes
`msdrg_get`	Look up an MS-DRG code
`msdrg_search`	Search MS-DRG codes
`pos_get`	Look up a Place of Service code
`jcode_by_hcpcs`	Find NDCs mapped to a J-code/HCPCS code
`jcode_by_ndc`	Find HCPCS codes mapped to an NDC
HCC / OPCS-4 Tools
`hcc_get`	Look up HCC risk adjustment mappings for an ICD-10 code
`hcc_reverse`	Find all ICD-10 codes mapping to a given HCC category
`hcc_search`	Search the HCC crosswalk by code, model, or category
`opcs4_get`	Look up an OPCS-4 UK NHS procedure code
`opcs4_search`	Search OPCS-4 procedure codes
dm+d Tools
`dmd_get`	Look up a UK dm+d medicine/device by SNOMED code
`dmd_search`	Search UK dm+d medicines and devices
UCUM Tools
`ucum_get`	Look up a UCUM unit code (e.g., mg, mL, kg/m2)
`ucum_search`	Search units of measure by name or description
`ucum_validate`	Validate a UCUM expression for correctness
`ucum_convert`	Convert a value between compatible UCUM units
RxClass Tools
`rxclass_get`	Look up a drug class by class ID
`rxclass_search`	Search drug classifications by name or type
`rxclass_members`	List drugs belonging to a drug class
DDI Tools
`check_drug_interactions`	Check drug-drug interactions for multiple drugs (FDA label text + RxNorm)
Batch Tools
`ndc_batch`	Look up multiple NDC codes (max 500)
`npi_batch`	Look up multiple NPI numbers (max 100)
`icd10_batch`	Look up multiple ICD-10 codes (max 100)
`rxnorm_batch`	Look up multiple RxCUIs (max 100)
`loinc_batch`	Look up multiple LOINC codes (max 100)
`cvx_batch`	Look up multiple CVX codes (max 100)
`mvx_batch`	Look up multiple MVX codes (max 100)
`fda_label_batch`	Look up multiple FDA labels (max 50)

Configuration Options

Environment Variable	Description	Default
`FHIRFLY_API_KEY`	Your FHIRfly API key (required)	-
`FHIRFLY_API_URL`	API base URL	`https://api.fhirfly.io`
`FHIRFLY_DEBUG`	Enable debug logging (`1` or `true`)	`false`
`FHIRFLY_TIMEOUT`	Fetch timeout in milliseconds	`30000`

Troubleshooting

"FHIRFLY_API_KEY environment variable is required"

Your API key isn't configured. Make sure:

You have a valid API key from fhirfly.io
It's set in the env section of your Claude Desktop config
The key starts with ffly_

"Invalid API key format"

FHIRfly API keys start with ffly_. Check that you copied the full key.

"Authentication failed"

Your API key may be invalid or expired. Generate a new one at fhirfly.io/dashboard/credentials.

Claude doesn't show FHIRfly tools

Make sure you completely quit and restarted Claude Desktop
Check your config file syntax (must be valid JSON)
Enable debug mode to see what's happening:

config.json

{
  "mcpServers": {
    "fhirfly": {
      "command": "npx",
      "args": ["-y", "@fhirfly-io/mcp-server"],
      "env": {
        "FHIRFLY_API_KEY": "your_key",
        "FHIRFLY_DEBUG": "1"
      }
    }
  }
}

"Rate limit exceeded"

You've hit your plan's rate limit. Wait a moment and try again, or upgrade your plan at fhirfly.io.

How It Works

Code

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│  Claude Desktop │────▶│  This Package   │────▶│  FHIRfly API    │
│                 │     │  (runs locally) │     │  (cloud)        │
│  "What is       │◀────│                 │◀────│                 │
│   NDC 123..."   │     │  Translates MCP │     │  Returns drug   │
│                 │     │  ↔ HTTPS        │     │  data           │
└─────────────────┘     └─────────────────┘     └─────────────────┘

This package runs on your computer as a bridge between Claude Desktop and the FHIRfly API. It:

Receives requests from Claude Desktop via stdin
Translates them to HTTPS requests to FHIRfly
Returns the results to Claude via stdout

Your API key is sent to FHIRfly over HTTPS. No healthcare data is stored locally.

Data Sources & Licensing

Data Source	Provider	License
NDC Directory	FDA	Public domain
NPPES (NPI)	CMS	Public domain
RxNorm	NLM (NIH)	UMLS license (free)
LOINC	Regenstrief Institute	Free with attribution
ICD-10-CM/PCS	CMS	Public domain
CVX/MVX	CDC	Public domain
FDA Drug Labels	FDA/openFDA	Public domain
SNOMED CT IPS	SNOMED International	CC BY 4.0
HCC Crosswalk	CMS	Public domain
OPCS-4	NHS England	OGL v3.0 (Crown copyright)
dm+d	NHS England / NHSBSA	OGL v3.0 (Crown copyright)
UCUM	NLM (NIH) / Regenstrief Institute	Free with attribution
RxClass	NLM (NIH)	UMLS license (free)
SMA Endpoint Directory	CMS	Public domain
HCPCS Level II	CMS	Public domain
MS-DRG	CMS	Public domain
Place of Service	CMS	Public domain
J-Code/NDC Crosswalk	CMS	Public domain
NCCI/MUE/PFS	CMS	Public domain
DDI Reference	FDA + NLM	Public domain

FHIRfly aggregates and indexes these data sources. See fhirfly.io/docs for details.

Changelog

See CHANGELOG.md for release history.

License

MIT - see LICENSE

Fhirfly MCP Server README