Connect citature to your agent.

The endpoint

Stateless — every request is independent, so there is no session to keep open and no handshake to resume. Any MCP client connects with the same block*:

{
  "mcpServers": {
    "citature": {
      "type": "http",
      "url": "https://mcp.citature.com/mcp"
    }
  }
}

Authorization

The free tools answer without one. Register the server, list the tools, and look up a food, a supplement label, a drug label, a substance or a reference amount — real receipts, cited to the record, before anything is agreed. The priced tools require a bearer token†, and so does a tool name the catalogue does not carry.

OAuth 2.1, with citature as the resource server. A client holding no token discovers where to get one from the protected-resource metadata, served without credentials:

https://mcp.citature.com/.well-known/oauth-protected-resource/mcp

Every step of obtaining one is a request an agent can make on its own, up to the single point a person signs in and approves the client: the credential walkthrough gives them in order — discovery, registering a client, the exchange, what each refusal code means, and how long a token lasts.

That person signs in to a citature account, and it is the account rather than the client that the approval is recorded against and that priced answers are billed to. The account's first priced answer starts its billing, with no card taken in advance: at the end of each monthly billing period an invoice for that period's priced answers is emailed to the account's address, to be paid on the hosted invoice page it links to. The terms set out what is billed and what never is, and refunds how a charge made in error is corrected. A client registers without an account and gets as far as the consent screen. Sign in, or ask to be told when accounts open.

Status. New accounts are not open yet: the sign-up page takes an address and writes to it when they are. Account billing runs in test mode: a priced answer is metered, and no money is taken for it. A payment made with a call settles on the Tempo test network, in test funds that carry no value.

Paying per call, without an account

Each tool is also an HTTP operation on the same host, POST /v1/tools/<name>, taking the tool's arguments as its JSON body and answering with the same receipt or estimate. A priced one can be paid for with the request, by an agent holding no account. The operations open to per-call payment, and the offer each is paid by, are listed in this document; an operation it lists without an x-payment-info offer is not open to it‡:

https://mcp.citature.com/openapi.json

Paid this way, a metered tool costs the second price its row among the tools carries, under what an account is billed. No payment made with a call is taken for less than $0.50, the least the payment processor records one for, so a call paid this way costs what an account is billed for it or $0.50, whichever is more.

The payment is sent only once the answer is in hand. An answer that found nothing is served free and sends nothing; a payment the network refuses withholds the answer, and citature takes nothing. A paid answer carries a Payment-Receipt header naming the transaction. The terms and refunds cover a per-call payment as they cover a billed call.

The tools

Of the 11, 7 restate a public record and cost nothing. The other 4 do the work nobody else assembles — one substance vocabulary across food, supplement and regulatory records — and those are metered per served answer.

What a call returns

An answer over a record comes back as a receipt; an answer over a survey sample comes back as an estimate, the receipt's sibling, carrying the survey design in place of a record identity.

What it cites

• USDA FoodData Centralfdc
• NIH ODS Dietary Supplement Label Databasedsld
• openFDAopenfda
• National Health and Nutrition Examination Survey (NHANES)nhanes
• FDA Substance Registration System (UNII)unii
• Electronic Code of Federal Regulationsecfr

Guardrails

These ship in the guardrails field of every answer and in the instructions the server hands over when an agent connects, which every tool description points to, so an agent reads them before it spends anything.

Not advice

Research over public records and product labels — not medical, nutritional, or safety advice.

No verdicts

citature reports what the record says. It never renders a verdict, a pass/fail, a diagnosis, or a recommendation, and is not a substitute for a clinician.

No individuals

Answers are product-, substance- or population-level only — foods, supplements, labels, substances, enforcement actions, and dietary intake as a weighted survey estimate. No answer returns or describes an individual person, and citature links no record to individually identifiable data.

Silence is not absence

A record that does not declare something is not a record declaring its absence. citature reports what a record states; it cannot report what a product does not contain, or what a population did not consume.

A Daily Value is not a DRI

A Daily Value is a labelling reference from federal regulation, not a Dietary Reference Intake. citature carries no licensed source for Dietary Reference Intakes and does not estimate whether anyone meets a nutrient requirement.