create_account

Create a send21 account for your human owner, without a key. The owner gets an email with a link to take the account over; until they do, nothing can be created. Returns a bootstrap API key ONCE (save it and send it as Authorization: Bearer on every later call; reconnect this MCP client with it). The key can read, propose addresses and check get_account_status; it can create pay links only after the owner took the account over and approved a receiving address you proposed. Agents onboard themselves; humans approve where the money lands. If the email already has an account, ask the owner for an API key instead.

Argument	Type	Description
agentName	string \| null	Your name as the owner will see it: letters, digits, spaces and . _ - ( ), at most 50
ownerEmail*	string	The human owner's email address (not yours); they receive the link to take the account over
intendedUse	string \| null	What you will use the account for, shown to the owner (max 300 characters)

Input schema (JSON)

{
  "type": "object",
  "required": [
    "ownerEmail"
  ],
  "properties": {
    "agentName": {
      "type": [
        "string",
        "null"
      ],
      "default": null,
      "description": "Your name as the owner will see it: letters, digits, spaces and . _ - ( ), at most 50"
    },
    "ownerEmail": {
      "type": "string",
      "description": "The human owner's email address (not yours); they receive the link to take the account over"
    },
    "intendedUse": {
      "type": [
        "string",
        "null"
      ],
      "default": null,
      "description": "What you will use the account for, shown to the owner (max 300 characters)"
    }
  }
}

create_draft

Create a non-custodial payment draft (you are the SENDER paying a receiver address). Amount is either exact base units (sats for BTC, micro-units for stablecoins, lamports for SOL, gwei for ETH) via amountBaseUnits, or fiat-pegged via fiatCurrency+fiatAmount with the exchange rate locked at creation. Returns the draft incl. id, amounts, fee, and status. Funds move only when the sender signs in their own wallet. send21 never holds keys. On accounts with the policy ApprovedOnly the receiver must be an address the owner approved (422 address_not_approved otherwise). Requires scope drafts:write.

Argument	Type	Description
memo	string \| null	Free-text memo shown on the draft (max 500 chars)
network*	string	Network: Mainnet, Solana, Ethereum, Base, Arbitrum, Polygon (test: Testnet4, Signet, Regtest, SolanaDevnet, EthereumSepolia, BaseSepolia, ArbitrumSepolia, PolygonAmoy)
currency	string \| null	Asset: Btc (default), Usdc, Usdt, Eurc, Sol (native SOL on Solana), or Eth (native ETH on Ethereum, Base, Arbitrum)
fiatAmount	number \| null	Fiat amount; requires fiatCurrency
fiatCurrency	string \| null	Fiat currency code for fiat-pegged amount, e.g. USD
idempotencyKey	string \| null	Idempotency key. A retry with the same key and the same parameters returns the original draft; the same key with another receiver, amount, currency or network is refused (422) and creates nothing

create_payment_request

Create a payment request / checkout pay link (you are the RECEIVER asking to get paid). Price in any of 161 fiat currencies; the payer opens the returned payPath, picks one of the offered currencies (rate locks then), and pays a single QR-scannable transfer straight to your address. On accounts with the policy ApprovedOnly (see get_account_status) every address must be one of the owner's approved receiving addresses; otherwise the answer is 422 address_not_approved and nothing is created (propose it with propose_receiving_address). Requires scope drafts:write.

Argument	Type	Description
memo	string \| null	Message shown to the payer (max 500 chars)
options*	array	Currencies the payer may choose from, each with your receiving address
orderId	string \| null	Your own order/reference id, echoed in webhooks for reconciliation
fiatAmount*	number	Amount in the fiat currency
declineNote	string \| null	What happens if the payer does not pay (plain text, max 200 chars). Shown on the pay page under the amount as "If you don't pay:". Use it when handing an over-budget purchase to a human, e.g. "The order is cancelled and the hotel room released at 18:00."
expiryHours	integer \| null	Hours until the request expires (default 24)

get_account_status

What stands between you and a live pay link: whether the owner's email is confirmed, the receiving-address policy, how many addresses are approved or waiting for approval, unsettled fees, your key's scopes, and the next steps. Requires scope drafts:read.

read-only

No arguments.

Input schema (JSON)

{
  "type": "object",
  "properties": {}
}

get_draft

Get a payment draft by id, including amounts, fee, quote, and status. Requires scope drafts:read.

read-only

Argument	Type	Description
draftId*	string	Draft id (GUID)

Input schema (JSON)

{
  "type": "object",
  "required": [
    "draftId"
  ],
  "properties": {
    "draftId": {
      "type": "string",
      "description": "Draft id (GUID)"
    }
  }
}

get_draft_status

Lightweight status snapshot of a draft: status (AwaitingPayment/Seen/Confirmed/Expired/Cancelled), paying txid, confirmations, and reviewState when a transfer with a different amount arrived (pending = needs the receiver's decision and the draft is not paid; accepted; rejected; unresolved = the draft expired while undecided, the money is with the receiver). Cheap to poll. Requires scope drafts:read.

read-only

Argument	Type	Description
draftId*	string	Draft id (GUID)

Input schema (JSON)

{
  "type": "object",
  "required": [
    "draftId"
  ],
  "properties": {
    "draftId": {
      "type": "string",
      "description": "Draft id (GUID)"
    }
  }
}

get_fee_schedule

Get the public send21 fee schedule: tiered percent by payment size in USD, min/max fee, and dust limit. No authentication needed.

read-only

No arguments.

Input schema (JSON)

{
  "type": "object",
  "properties": {}
}

get_payment_request

Get a payment request by id: status (Open/Completed/Cancelled/Expired), pay path, offered currencies, and the underlying draft once the payer committed. Includes changeSignals and changeNotes: what is unusual compared with the account's paid payments (new_address, new_asset, unusual_amount), the same lines the payer sees on the pay page; empty when nothing is unusual. Requires scope drafts:read.

read-only

Argument	Type	Description
paymentRequestId*	string	Payment request id (GUID)

Input schema (JSON)

{
  "type": "object",
  "required": [
    "paymentRequestId"
  ],
  "properties": {
    "paymentRequestId": {
      "type": "string",
      "description": "Payment request id (GUID)"
    }
  }
}

get_rate

Get the current exchange rate for an asset in a fiat currency (rate = fiat units per 1 whole asset unit, with source provenance). Assets: Btc, Usdc, Usdt, Eurc, Sol, Eth. 161 ISO 4217 fiat currencies are supported. Requires an API key.

read-only

Argument	Type	Description
asset*	string	Asset: Btc, Usdc, Usdt, Eurc, Sol, or Eth
fiatCurrency*	string	Fiat currency code, e.g. USD, EUR, SEK

Input schema (JSON)

{
  "type": "object",
  "required": [
    "fiatCurrency",
    "asset"
  ],
  "properties": {
    "asset": {
      "type": "string",
      "description": "Asset: Btc, Usdc, Usdt, Eurc, Sol, or Eth"
    },
    "fiatCurrency": {
      "type": "string",
      "description": "Fiat currency code, e.g. USD, EUR, SEK"
    }
  }
}

get_transaction_template

Get the transaction template for an on-chain draft: every output to pay, plus walletcreatefundedpsbt arguments and a pay-to-many CSV on Bitcoin, or payment URIs (and calldata on EVM chains) on Solana, Ethereum, Base, Arbitrum and Polygon. The sender's own wallet funds, reviews and signs it; send21 contains no signing code. Not for Lightning drafts (pay their invoice). Requires scope drafts:read.

read-only

Argument	Type	Description
draftId*	string	Draft id (GUID)

Input schema (JSON)

{
  "type": "object",
  "required": [
    "draftId"
  ],
  "properties": {
    "draftId": {
      "type": "string",
      "description": "Draft id (GUID)"
    }
  }
}

list_address_book

List the account's saved addresses (label, address, network, direction: Sending = recipients the owner pays, Receiving = the owner's own addresses). Requires scope addressbook:read.

read-only

No arguments.

Input schema (JSON)

{
  "type": "object",
  "properties": {}
}

list_draft_quotes

List every quote (rate lock) of a fiat-priced draft, oldest first. Quotes never change; a re-quote adds a new one with its own id. Each has a sha256 (RFC 8785 JCS + SHA-256). Requires scope drafts:read.

read-only

Argument	Type	Description
draftId*	string	Draft id (GUID)

Input schema (JSON)

{
  "type": "object",
  "required": [
    "draftId"
  ],
  "properties": {
    "draftId": {
      "type": "string",
      "description": "Draft id (GUID)"
    }
  }
}

propose_receiving_address

Propose an address for the owner to approve: one of the owner's own receiving addresses (for pay links) or the address of someone the owner pays (for drafts). It is saved unapproved and the owner gets an email. On accounts with the policy ApprovedOnly, API keys can only use approved addresses, and only the owner can approve one, signed in to the send21 app with a passkey or authenticator code. No key can approve an address. Requires scope addressbook:write.

Argument	Type	Description
label*	string	A label the owner will recognise, e.g. "My Phantom wallet" (unique per account)
address*	string	The address, or for BTC over Lightning the Lightning address ([email protected])
network*	string	Network the address lives on: Mainnet (Bitcoin, also for Lightning addresses), Solana, Ethereum, Base, Arbitrum or Polygon
direction	string \| null	Receiving (default): the owner's own address, for pay links. Sending: someone the owner pays, for drafts.

Input schema (JSON)

{
  "type": "object",
  "required": [
    "label",
    "address",
    "network"
  ],
  "properties": {
    "label": {
      "type": "string",
      "description": "A label the owner will recognise, e.g. \"My Phantom wallet\" (unique per account)"
    },
    "address": {
      "type": "string",
      "description": "The address, or for BTC over Lightning the Lightning address ([email protected])"
    },
    "network": {
      "type": "string",
      "description": "Network the address lives on: Mainnet (Bitcoin, also for Lightning addresses), Solana, Ethereum, Base, Arbitrum or Polygon"
    },
    "direction": {
      "type": [
        "string",
        "null"
      ],
      "default": null,
      "description": "Receiving (default): the owner's own address, for pay links. Sending: someone the owner pays, for drafts."
    }
  }
}

submit_lightning_proof

Confirm a paid Lightning draft with its proof of payment: the 64-character preimage the paying wallet shows after a Lightning payment. Needed for drafts with a pasted bolt11 invoice, and for Lightning addresses whose provider does not report payments. send21 checks that SHA-256 of the preimage equals the invoice's payment hash; the draft then confirms within about 30 seconds. Requires scope drafts:write.

Argument	Type	Description
draftId*	string	Draft id (GUID)
preimage*	string	Payment preimage, 64 hex characters

Input schema (JSON)

{
  "type": "object",
  "required": [
    "draftId",
    "preimage"
  ],
  "properties": {
    "draftId": {
      "type": "string",
      "description": "Draft id (GUID)"
    },
    "preimage": {
      "type": "string",
      "description": "Payment preimage, 64 hex characters"
    }
  }
}

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