Insurance Denials MCP Server

insurance-denials

US health-insurance claim denial rates and appeal outcomes, per insurer — which companies deny the most claims, and whether appealing one actually works.

Part of Pipeworx — an MCP gateway connecting AI agents to 1865+ live data sources. This is an independent, unofficial integration — not affiliated with, endorsed by, or published by the upstream provider.

Tools

Auth

None. No key, no account.

Data sources

The CMS Transparency in Coverage Public Use File, plan year 2026, published by the Centers for Medicare & Medicaid Services:

• Landing page: https://www.cms.gov/marketplace/resources/data/public-use-files
• File: https://download.cms.gov/marketplace-puf/2026/transparency-in-coverage-puf.zip

Issuers report these figures to CMS themselves under 45 CFR 156.220. CMS publishes the file once a year, as an XLSX inside a ZIP.

What this covers, and what it does not

Two limits, both easy to mistake for a data bug:

HealthCare.gov states only — 30 of them. An issuer on a state-run exchange (California, New York, Massachusetts, Washington, Colorado, Pennsylvania, New Jersey and others) reports to that state, not into this federal file. A caller asking about California gets an explicit state_not_in_source refusal naming the reason, rather than an empty list that would read as "California insurers deny nothing".

Self-reported. These are the issuers' own counts, and CMS says so in the file's own disclaimer. They are not an audit.

Reading the numbers

• Dental denies far more than medical. Standalone dental plans (Individual SADP) sit at the top of any unfiltered denial ranking — several above 70%. Pass market: "medical" when the question is about medical cover, or the answer will be true and misleading.
• Suppressed is not zero. CMS marks a figure it cannot publish with * or **. Those are null here, never 0 — a suppressed denial count reported as zero would describe a perfect insurer.
• Internal and external appeals differ. Internal appeals are decided by the insurer that issued the denial; external appeals go to an independent reviewer. The external number is the arm's-length one.
• One filing per state. A multi-state insurer reports separately in each state, so insurer_denial_profile returns one entry per state rather than a single national figure.
• markets is a scope label, not a slice. CMS publishes these counts per ISSUER, not per market, and an issuer selling both medical and dental files the same totals in both sheets (25 of 348 do). So markets lists which marketplaces an issuer participates in, and filtering by market chooses which issuers to include — it does not carve up their claim counts.

Refreshing

Annual, when CMS publishes the next plan year:

node scripts/refresh-insurance-denials.mjs   # rewrites src/data.json

The script re-reads the CMS file and rolls it up to issuer level. It dedupes by issuer id and never sums: the Issuer_* columns repeat identically on every plan row an issuer has, so summing multiplies each figure by that issuer's plan count. Verified when the pack was built — 0 of 185 issuer ids varied across their own rows. It also emits one record per issuer, merging the market sheets an issuer appears in, for the same reason: those rows carry identical totals, and one row per sheet duplicated 25 issuers in every ranking.

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "insurance-denials": {
      "url": "https://gateway.pipeworx.io/insurance-denials/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/insurance-denials/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — ask_pipeworx, discover_tools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

This is deliberate, not multiplexing by accident. The meta-tools are what let a scoped connection answer a question this pack does not cover — via ask_pipeworx, which routes across the whole catalog — without you adding a second MCP server. There is currently no way to mount a pack endpoint without them; if the extra schemas cost you more context than the routing is worth, connect to the full gateway once rather than to several pack endpoints.

Or connect to the full Pipeworx gateway to get every pack's tools listed directly, instead of just this one's:

{
  "mcpServers": {
    "pipeworx": {
      "url": "https://gateway.pipeworx.io/mcp"
    }
  }
}

Both URLs reach the same gateway and the same 1865+ data sources. The only difference is which pack's tools are listed directly; ask_pipeworx reaches all of them from either one.

No MCP client? Call it over HTTP

curl -X POST https://gateway.pipeworx.io/v1/tools/insurer_denial_rates \
  -H 'Content-Type: application/json' \
  -d '{"market":"medical","limit":5}'

No account needed for the first calls. Inspect any tool: GET https://gateway.pipeworx.io/v1/tools/insurer_denial_rates. Find one: POST https://gateway.pipeworx.io/v1/tools/search_packs with {"query":"..."}.

Run it from npm

@pipeworx/mcp-insurance-denials is a local stdio bridge to the Pipeworx gateway: your MCP client starts it with npx, and it forwards every call to the same https://gateway.pipeworx.io/insurance-denials/mcp endpoint shown above. It needs network access; there is no offline mode.

{
  "mcpServers": {
    "insurance-denials": {
      "command": "npx",
      "args": ["-y", "@pipeworx/mcp-insurance-denials"]
    }
  }
}

Without a key it calls anonymously, capped at 50 calls a day. A free account raises that to 200 a day: get a key at https://pipeworx.io/signup and add "env": { "PIPEWORX_API_KEY": "<your key>" } to the server entry. The key is sent as a Bearer token, the same way a hosted connection sends it, so calls are metered and billed exactly as they are there.

It lists only this pack's tools by default. Set PIPEWORX_META_TOOLS=1 to also list ask_pipeworx and the other gateway-wide tools.

Behind an HTTPS proxy: Node's built-in fetch does not read HTTPS_PROXY by default. Newer Node releases honour it when NODE_USE_ENV_PROXY=1 is set; check your Node version's documentation.

Using with ask_pipeworx

Instead of calling tools directly, you can ask questions in plain English — this works on the pack endpoint above as well as on the full gateway:

ask_pipeworx({ question: "your question about Insurance Denials data" })

The gateway picks the right tool and fills the arguments automatically.

More

• Docs and guides
• pipeworx.io

License

MIT