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Marketplace API (BYOK) — connector documentation

  • MCP endpoint: https://byok-cmsmarketplace.connectorbay.com/mcp
  • REST API: POST https://byok-cmsmarketplace.connectorbay.com/v1/tools/{tool_name}, described by the OpenAPI 3.1 spec at https://byok-cmsmarketplace.connectorbay.com/openapi.json
  • Transport: Streamable HTTP, stateless, MCP specification 2025-06-18 or later
  • Authentication: your own Marketplace API Marketplace API key, sent in the X-Upstream-Key header of every request (never stored, logged or cached)
  • Health: https://byok-cmsmarketplace.connectorbay.com/health · Tool schemas: https://byok-cmsmarketplace.connectorbay.com/tools.json
  • Publisher: Unify Dynamics LLC · connectorbay.com/byok-cmsmarketplace · agent@connectorbay.com

What Marketplace API (BYOK) is for

Marketplace API (BYOK) lets an AI assistant read your own Marketplace API data through the Marketplace API API with a key you supply (Marketplace API key). Read-only: 10 tools (get_market_years, list_counties_by_zip, list_issuers, get_issuer, search_plans, get_plan, get_lowest_cost_silver_plan, get_second_lowest_cost_silver_plan, search_drugs, get_poverty_level_percent). The BYOK key travels with each request, is used for that one call only and is never stored, logged or cached; it is only ever sent to marketplace.api.healthcare.gov. Unofficial connector by Unify Dynamics LLC: not affiliated with, endorsed by or sponsored by Marketplace API. Marketplace API and its logos are trademarks of their owners and are used only to say which service the connector works with.

Ask your assistant things like:

  • "Which plan years does the Marketplace API cover?"
  • "Which county is ZIP code 27360 in?"
  • "Which health insurers sell plans on the exchange in North Carolina?"
  • "Show details of exchange issuer 45127."
  • "What Silver plans are available for a 27-year-old earning 52000 in ZIP 27360?"
  • "Show plan 45127PA0020020 from the exchange."

What it does

  • get_market_years: List the market years the Marketplace API supports and which one is current.
  • list_counties_by_zip: Find the counties (name, state and 5-digit FIPS code) that a ZIP code or ZIP prefix belongs to; the FIPS code is needed for plan searches.
  • list_issuers: List health insurance issuers (name, 5-digit issuer id, state, toll-free number) on the exchange, optionally for one state.
  • get_issuer: Get one issuer by its 5-digit HIOS id: name, state, customer service numbers and plan URLs.
  • search_plans: Quote exchange plans for a single applicant: monthly premium (with and without subsidy), metal level, plan type and issuer, sorted as requested. Returns 10 plans per page.
  • get_plan: Get one plan by its 14-character HIOS id: name, issuer, metal level, type, state and links to its benefits, brochure, formulary and network.
  • get_lowest_cost_silver_plan: Find the lowest cost Silver plan for a single applicant in a county: plan id, name and monthly premium.
  • get_second_lowest_cost_silver_plan: Find the second lowest cost Silver plan (the benchmark for subsidies) for a single applicant in a county.
  • search_drugs: Search prescription drugs by name; returns drug ids, names, strengths and routes, which can be used to check plan formularies.
  • get_poverty_level_percent: Compute a household's income as a percentage of the federal poverty level for a state, year and household size.

BYOK key

You bring your own Marketplace API Marketplace API key (https://developer.cms.gov/marketplace-api/key-request.html). Your assistant sends it in the X-Upstream-Key header with each request. ConnectorBay uses it for that one call only: it is never stored, logged or cached, never shown in an answer, and it is only sent to marketplace.api.healthcare.gov over https, with no redirects followed. Create a key with the fewest permissions the tools need (read-only if the provider offers it), and revoke it at the provider whenever you like.

Data sources

Live from the Marketplace API API (marketplace.api.healthcare.gov) with a BYOK key; documentation: https://developer.cms.gov/marketplace-api/api-spec. Endpoints checked against that documentation on 2026-10-16.

What it is not

Unofficial connector by Unify Dynamics LLC: not affiliated with, endorsed by or sponsored by Marketplace API. Marketplace API and its logos are trademarks of their owners and are used only to say which service the connector works with. It is read-only: it never creates, changes, sends or deletes anything in your Marketplace API account.

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