@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

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

Quick Setup

Step 1: Get a FHIRfly API Key

1. Go to fhirfly.io and sign up
2. Navigate to Dashboard > Credentials
3. Click Create Credential and select MCP (Claude Desktop)
4. 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:

{
  "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

Configuration Options

Troubleshooting

"FHIRFLY_API_KEY environment variable is required"

Your API key isn't configured. Make sure:

1. You have a valid API key from fhirfly.io
2. It's set in the env section of your Claude Desktop config
3. 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

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

{
  "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

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│  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:

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

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

Links

• FHIRfly Documentation
• MCP Setup Guide
• Get an API Key
• Report Issues

Data Sources & Licensing

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

Changelog

See CHANGELOG.md for release history.

License

MIT - see LICENSE