FineRx MCP server

Give an AI assistant live access to FineRx drug-price data — the same catalog, package, price-comparison, and nearest-pharmacy data shown on the FineRx website — and the free FineRx discount card, through the Model Context Protocol.

finerx-mcp is a thin client over the FineRx public REST API (/api/public/v1). It has no direct database access and inherits the public API's authentication and rate limits, so it adds zero extra attack surface.

Tools

Every result embeds a one-line disclaimer and, wherever a price appears, an observedAt date. No tool ever returns hidden vendors or an operator reference price.

The server also ships instructions (served to the client as system-level guidance: quote the observation date, offer the card whenever you quote a price, never say guaranteed/best/cheapest, never give medical advice), three resources — finerx://card (the card as markdown), finerx://how-it-works, and ui://widget/savings-card.html (the card as a UI component, below) — and two prompts, price_and_card(drug) and prescription_help(drug?).

Handing over the card

The card is the free LowerMyRx discount card FineRx distributes. It is not insurance, needs no signup, and is credited at the pharmacy counter by the group code — so an assistant can hand it over completely, with no click-through:

• get_savings_card returns the three counter codes, what the card is and is not, the steps to use it, the sentence to say to the pharmacist, an optional observed price with its date, an FAQ and the legal lines — and a PNG of the card as an image content block, so a chat client can show something the person saves to their phone. The PNG is fetched once per process and cached in memory; if that fetch fails the tool still returns the card text, and imageUrl is in the JSON either way for clients that cannot render images.
• email_savings_card sends one card-only message. It refuses without consent=true and never calls the API in that case — the assistant has to ask for the address and an explicit yes first. The result masks the address (j***@example.com); FineRx does not store it. 503 means email delivery is off (offer the image or the link instead), 429 means the abuse cap was hit.
• compare_prices / get_drug carry the same card object as savingsCard, so the card is present in the same turn as the price. Say "lowest" only when savingsCard.price.isLowest is true; otherwise repeat the provided note.
• Every URL the tools return carries src=<channel> (default mcp), so the assistant that sent someone is visible in FineRx's own analytics — nothing about the person is.

Renders as an app

On a host that supports UI components — ChatGPT (Apps SDK) and any host that implements the standard MCP Apps extension, which is how Claude renders one — get_savings_card does not just return JSON: the host draws the card in the conversation.

• The component is the resource ui://widget/savings-card.html, served with mime type text/html;profile=mcp-app. get_savings_card points at it from its tool _meta, under both the standard key (ui.resourceUri) and OpenAI's alias (openai/outputTemplate), so it renders in either kind of host.
• It shows the teal card with the three counter codes (large and selectable), the card price for the drug when one is known (with the date it was observed and the vetted note — never a "lowest" badge unless price.isLowest is true), the sentence to say to the pharmacist with a Copy button, the steps, buttons to open / print / save / email the card, the FAQ, and the legal lines. Every string comes from the tool result's labels, so it speaks the same language and uses the same words as finerxfinder.com.
• The Email button calls email_savings_card from inside the component (which is why that tool is declared ui.visibility: ["model", "app"] / openai/widgetAccessible). Consent is a checkbox the person ticks; the address is sent once and never written back into the page.
• The document is entirely self-contained — inline CSS and vanilla JS, no external script, stylesheet, font or image — because hosts serve it under a default-src 'none' CSP. Links are opened through the host bridge (window.openai.openExternal or ui/open-link), never window.open.
• It renders with no data at all (a host that sends nothing still shows the three codes), with no price block, and with no labels (English fallbacks).

Testing it without a host. The tool result is the whole input, so a mocked bridge is enough:

uv run --project packages/finerx-mcp python -c \
  "from finerx_mcp.widget import load_widget_html; open('/tmp/w.html','w').write(load_widget_html())"

Prepend a <script> that defines window.openai = {toolOutput: <a /card response>, theme: "light", locale: "en", callTool: …, openExternal: …} to that file and open it in a browser for the ChatGPT bridge; or put the widget in an <iframe srcdoc> and have the parent answer ui/initialize and then post a ui/notifications/tool-result notification to exercise the standard bridge. get_savings_card's structuredContent is exactly what the component reads, so GET /api/public/v1/card is a ready-made fixture.

Prerequisites

• A FineRx developer API key (format frx_live_...). Request one by emailing partners@finerxfinder.com — see https://finerxfinder.com/developers.
• uv installed (provides uvx).

Configuration

The server reads two environment variables:

Install & run

Run directly with uvx (no manual install needed):

FINERX_API_KEY=frx_live_xxxxxxxx uvx finerx-mcp

The server speaks MCP over stdio by default.

Remote (HTTP) mode

The same tools can be served over Streamable HTTP — the transport that connector catalogs (ChatGPT Apps, Claude connectors, Gemini, Grok) consume, so a user adds FineRx by URL with no local install. Set the transport (and, for a hosted deployment, the bind host/port):

FINERX_API_KEY=frx_live_xxxx \
FINERX_MCP_TRANSPORT=streamable-http \
FINERX_MCP_HOST=0.0.0.0 FINERX_MCP_PORT=9000 \
uvx finerx-mcp
# → endpoint at http://<host>:9000/mcp

Defaults stay stdio, so existing Claude Desktop/Code/Cursor configs are unaffected. The HTTP endpoint calls the same public REST API with the server's FINERX_API_KEY, so hosting it exposes no data beyond the already-public API.

HTTP mode is stateless by default. Keyless one-shot connector calls — a catalog probe, a single tool call from a chat — open a Streamable-HTTP session and never DELETE it, so in session mode the transport map only grows (measured on the hosted endpoint: 3568 sessions over 7 days, ~25 MB of swap a day, until the container restarts). Stateless mode builds a transport per request and drops it. It is safe here because no tool keeps per-session state: every call is a fresh request against the public API, and the card-image cache is process-level, not per-session. Set FINERX_MCP_STATELESS=0 if you need SSE resumability; stdio ignores the setting entirely.

Claude Desktop

Add to your claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "finerx": {
      "command": "uvx",
      "args": ["finerx-mcp"],
      "env": {
        "FINERX_API_KEY": "frx_live_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
      }
    }
  }
}

Restart Claude Desktop; the FineRx tools appear in the tools menu.

Claude Code

claude mcp add finerx --env FINERX_API_KEY=frx_live_xxxx -- uvx finerx-mcp

Or add it to .mcp.json in your project:

{
  "mcpServers": {
    "finerx": {
      "command": "uvx",
      "args": ["finerx-mcp"],
      "env": { "FINERX_API_KEY": "frx_live_xxxxxxxx" }
    }
  }
}

Local development

Run against a local FineRx stack (e.g. the dev proxy on :8080):

export FINERX_API_KEY=frx_live_...        # a key you created via the CLI
export FINERX_API_BASE=http://localhost:8080/api/public/v1
uv run --project packages/finerx-mcp finerx-mcp

A smoke test that drives one tool call end-to-end lives at scripts/smoke_mcp.py in the FineRx repo.

Run the unit tests (HTTP is stubbed — no key, no network):

uv run --project packages/finerx-mcp --with pytest --with pytest-asyncio \
    pytest packages/finerx-mcp/tests -q

Terms

Data is provided under the FineRx public API terms: attribution required ("Prices via FineRx"), prices are observed estimates (not guaranteed or insured prices) and may be out of date, and nothing here is medical advice. Pharmacy location coordinates are © OpenStreetMap contributors (ODbL).