FHIR R4 MCP server — read, search, paginate, validate resources against US Core/IPS profiles, and authenticate against Epic/Cerner EHR sandboxes via SMART-on-FHIR OAuth 2.0.
Part of the fhir-mcp-suite monorepo.

What it does

mcp-fhir exposes five MCP tools that let any MCP-compatible AI (Claude, GPT-4o, etc.) interact with any FHIR R4 server — and validate resources against US Core and IPS profiles — in a single server process. No other public FHIR MCP server combines search + validation today.

Tool	Description
`fhir_capabilities`	CapabilityStatement summary — what the server supports
`fhir_read`	Read a single resource by type + logical ID
`fhir_search`	Search a resource type with FHIR query params; returns Bundle with `_next_url` when paginated
`fhir_search_next`	Follow a `_next_url` pagination link (SSRF-guarded)
`validate_against_profile`	Validate a resource via the HAPI validator; supports US Core & IPS aliases

Architecture

Claude Desktop / AI client
        │  MCP (stdio or SSE)
        ▼
┌───────────────────────────────┐
│        mcp-fhir  v1.1         │
│  ┌───────────────────────────┐│
│  │  tools/                   ││
│  │  ├─ fhir_capabilities.py  ││
│  │  ├─ fhir_read.py          ││
│  │  ├─ fhir_search.py        ││   ──► FHIR R4 server
│  │  └─ validate_profile.py   ││   ──► HAPI validator sidecar
│  └───────────────────────────┘│
│  fhir-mcp-shared               │
│  ├─ LangFuse traces (session)  │
│  ├─ Pydantic structured output │
│  └─ structlog JSON logging     │
└───────────────────────────────┘

Quick start

# requires Python 3.12+ and uv
uvx mcp-fhir           # stdio transport (Claude Desktop, default)

# SSE transport (HTTP, for API access)
MCP_TRANSPORT=sse uvx mcp-fhir

Claude Desktop config (`claude_desktop_config.json`)

{
  "mcpServers": {
    "mcp-fhir": {
      "command": "uvx",
      "args": ["mcp-fhir"],
      "env": {
        "FHIR_BASE_URL": "https://hapi.fhir.org/baseR4",
        "HAPI_VALIDATOR_URL": "http://localhost:8082"
      }
    }
  }
}

See full installation guide for HAPI validator setup, troubleshooting, and self-hosted FHIR server configuration.

Eval results

Golden query suite — run against the public HAPI demo server (hapi.fhir.org/baseR4):

Category	Cases	Pass rate
`fhir_capabilities`	2	100 %
`fhir_read`	4	100 %
`fhir_search`	6	100 %
`fhir_search_next`	2	100 %
`validate_against_profile`	6	100 %
Total	20	100 %

CI gate: uv run python evals/mcp-fhir/run_eval.py --ci --threshold 0.9
Validator cases require the HAPI sidecar (docker compose up hapi-validator).

Configuration

All settings via environment variables (see .env.example):

Variable	Default	Description
`FHIR_BASE_URL`	`https://hapi.fhir.org/baseR4`	FHIR server base URL
`HAPI_VALIDATOR_URL`	`http://localhost:8082`	HAPI validator sidecar (runs on port 3500 internally; map `8082:3500`)
`FHIR_TIMEOUT_S`	`30`	HTTP timeout in seconds
`FHIR_MAX_RESULTS`	`20`	Default `_count` for searches
`MCP_TRANSPORT`	`stdio`	`stdio` or `sse`
`MCP_PORT`	`8000`	Port for SSE transport
`LOG_FORMAT`	`json`	`json` (prod) or `console` (dev)
`LANGFUSE_PUBLIC_KEY`	(unset)	LangFuse observability (optional)
`LANGFUSE_SECRET_KEY`	(unset)	LangFuse observability (optional)

SMART-on-FHIR authentication

mcp-fhir v1.1.0 adds SMART-on-FHIR backend services (client_credentials grant, RFC 6749) so the server can authenticate against real Epic / Cerner sandboxes — no browser redirect needed.

When SMART_ENABLED=true, every FHIR request gets an Authorization: Bearer <token> header. Tokens are cached in-process and refreshed automatically 30 s before expiry.

SMART environment variables

Variable	Default	Description
`SMART_ENABLED`	`false`	Set `true` to activate SMART auth
`SMART_CLIENT_ID`	`""`	App client ID from EHR registration portal
`SMART_CLIENT_SECRET`	`""`	Client secret (stored as `SecretStr`, never logged)
`SMART_TOKEN_URL`	`""`	Token endpoint URL; auto-discovered if blank
`SMART_SCOPES`	`system/*.read`	Space-separated OAuth 2.0 scopes
`SMART_GRANT_TYPE`	`client_credentials`	OAuth grant type (only `client_credentials` supported)
`SMART_TOKEN_TIMEOUT_S`	`15.0`	HTTP timeout for token requests

When SMART_TOKEN_URL is blank the server performs SMART auto-discovery:
GET {FHIR_BASE_URL}/.well-known/smart-configuration → token_endpoint.
Falls back to {FHIR_BASE_URL}/oauth2/token if discovery returns a non-200.

Epic sandbox quick-start

Register at https://fhir.epic.com/ → My Apps → create a backend-services app.
Note your Client ID and Client Secret.
Create .env in the monorepo root (already in .gitignore):

FHIR_BASE_URL=https://fhir.epic.com/interconnect-fhir-oauth/api/FHIR/R4
SMART_ENABLED=true
SMART_CLIENT_ID=your-epic-client-id
SMART_CLIENT_SECRET=your-epic-client-secret
# SMART_TOKEN_URL is optional — auto-discovered from FHIR_BASE_URL

Cerner sandbox quick-start

Register at https://code.cerner.com/ → create a backend-services app.
Note your Client ID and the token endpoint URL.
Update .env:

FHIR_BASE_URL=https://fhir-ehr-code.cerner.com/r4/your-tenant-id
SMART_ENABLED=true
SMART_CLIENT_ID=your-cerner-client-id
SMART_CLIENT_SECRET=your-cerner-client-secret
SMART_TOKEN_URL=https://authorization.cerner.com/tenants/your-tenant-id/protocols/oauth2/profiles/smart-v1/token

Claude Desktop config with SMART auth

{
  "mcpServers": {
    "mcp-fhir": {
      "command": "uvx",
      "args": ["mcp-fhir"],
      "env": {
        "FHIR_BASE_URL": "https://fhir.epic.com/interconnect-fhir-oauth/api/FHIR/R4",
        "SMART_ENABLED": "true",
        "SMART_CLIENT_ID": "your-epic-client-id",
        "SMART_CLIENT_SECRET": "your-epic-client-secret"
      }
    }
  }
}

Programmatic client (LangGraph / any Python agent)

Use StdioServerParameters to point any Python MCP client at a FHIR server. The same pattern works in LangGraph tool nodes, LangChain agents, or plain asyncio scripts.

from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client
import asyncio, os

server = StdioServerParameters(
    command="uv",
    args=["run", "--package", "mcp-fhir", "mcp-fhir"],
    env={
        **os.environ,
        # ── Public HAPI (no auth) ──────────────────────────────────
        "FHIR_BASE_URL": "https://hapi.fhir.org/baseR4",
        "SMART_ENABLED": "false",

        # ── Epic sandbox (uncomment + fill in) ────────────────────
        # "FHIR_BASE_URL":       "https://fhir.epic.com/interconnect-fhir-oauth/api/FHIR/R4",
        # "SMART_ENABLED":       "true",
        # "SMART_CLIENT_ID":     os.environ["EPIC_CLIENT_ID"],
        # "SMART_CLIENT_SECRET": os.environ["EPIC_CLIENT_SECRET"],

        # ── Cerner sandbox (uncomment + fill in) ──────────────────
        # "FHIR_BASE_URL":       "https://fhir-myrecord.cerner.com/r4/<tenant-id>",
        # "SMART_ENABLED":       "true",
        # "SMART_CLIENT_ID":     os.environ["CERNER_CLIENT_ID"],
        # "SMART_CLIENT_SECRET": os.environ["CERNER_CLIENT_SECRET"],
        # "SMART_TOKEN_URL":     "https://authorization.cerner.com/tenants/<tenant-id>/...",
    },
)

async def main():
    async with stdio_client(server) as (read, write):
        async with ClientSession(read, write) as session:
            await session.initialize()
            result = await session.call_tool(
                "fhir_search",
                arguments={"resource_type": "Patient", "params": {"_count": "3"}},
            )
            print(result.content[0].text)

asyncio.run(main())

See demo/fhir_server_configs.py for ready-to-run configs for all supported servers (public HAPI, SMART Health IT, Epic, Cerner, local Docker).

Running SMART integration tests

# Requires real sandbox credentials in .env
uv run pytest packages/mcp-fhir/tests -m smart_integration -v

Profile validation

The validate_against_profile tool supports shorthand aliases:

Alias	Profile URL
`us-core-patient`	`http://hl7.org/fhir/us/core/StructureDefinition/us-core-patient`
`us-core-observation`	`http://hl7.org/fhir/us/core/StructureDefinition/us-core-observation-clinical-result`
`us-core-condition`	`http://hl7.org/fhir/us/core/StructureDefinition/us-core-condition-problems-health-concerns`
`us-core-medication-request`	`http://hl7.org/fhir/us/core/StructureDefinition/us-core-medicationrequest`
`us-core-encounter`	`http://hl7.org/fhir/us/core/StructureDefinition/us-core-encounter`
`ips-patient`	`http://hl7.org/fhir/uv/ips/StructureDefinition/Patient-uv-ips`

Profile validation requires the HAPI validator sidecar (included in docker-compose.yml at repo root).

Development

# From monorepo root
uv sync
uv run pytest packages/mcp-fhir/tests -v
# Integration tests (requires HAPI public server access)
uv run pytest packages/mcp-fhir/tests -m integration

Architecture

Client (Claude / GPT-4o)
    │  MCP protocol (stdio or SSE)
    ▼
mcp-fhir server (Python, anyio)
    ├── fhir_read ──────────► FHIR R4 server (configurable)
    ├── fhir_search ─────────► FHIR R4 server
    └── validate_against_profile
              │
              ▼
        HAPI validator sidecar (markiantorno/validator-wrapper)
              │
              ▼
        LangFuse (optional observability)