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send21

by send21io · remote · no sign-in to list tools · v1.5.0 · published by GitHub user send21io

Crypto pay links and API for people and AI agents. BTC, Lightning, USDC, USDT, EURC, SOL, ETH.

Final · 1Changes · 4
CompareRegistry entry

14 tools: 1 do something that can't be undone, 4 change things and 9 only read.

Scanned Oct 21, 2026

No check matched anything in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http send21io https://send21.io/mcp

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

14 tools

Can't be undone 1Claude Code: ask
  • create_payment_requestCreate a payment request / checkout pay link (you are the RECEIVER asking to get paid).No findings

    Why it is in this group

    • The name "create_payment_request" says "create": a word for a change.
    • The name "create_payment_request" also says "payment": a word that usually means money moves, which cannot be taken back.
    Description, as the server wrote it
    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.
Changes things 4Claude Code: ask
  • create_accountCreate a send21 account for your human owner, without a key.No findings

    Why it is in this group

    • The name "create_account" says "create": a word for a change.
    Description, as the server wrote it
    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.
  • create_draftCreate a non-custodial payment draft (you are the SENDER paying a receiver address).No findings

    Why it is in this group

    • The name "create_draft" says "create": a word for a change.
    Description, as the server wrote it
    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.
  • propose_receiving_addressPropose 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).No findings

    Why it is in this group

    • Nothing in its name or description says what it does, so it is counted as a write.
    Description, as the server wrote it
    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.
  • submit_lightning_proofConfirm a paid Lightning draft with its proof of payment: the 64-character preimage the paying wallet shows after a Lightning payment.No findings

    Why it is in this group

    • The name "submit_lightning_proof" says "submit": a word for a change.
    Description, as the server wrote it
    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.
Only reads 9Claude Code: allow
  • get_account_statusWhat 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, unsettle…No findings

    Why it is in this group

    • The name "get_account_status" says "get": a word for reading.
    Description, as the server wrote it
    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.
  • get_draftGet a payment draft by id, including amounts, fee, quote, and status.No findings

    Why it is in this group

    • The name "get_draft" says "get": a word for reading.
    Description, as the server wrote it
    Get a payment draft by id, including amounts, fee, quote, and status. Requires scope drafts:read.
  • get_draft_statusLightweight status snapshot of a draft: status (AwaitingPayment/Seen/Confirmed/Expired/Cancelled), paying txid, confirmations, and reviewState when a transfer with a different amou…No findings

    Why it is in this group

    • The name "get_draft_status" says "get": a word for reading.
    Description, as the server wrote it
    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.
  • get_fee_scheduleGet the public send21 fee schedule: tiered percent by payment size in USD, min/max fee, and dust limit.No findings

    Why it is in this group

    • The name "get_fee_schedule" says "get": a word for reading.
    Description, as the server wrote it
    Get the public send21 fee schedule: tiered percent by payment size in USD, min/max fee, and dust limit. No authentication needed.
  • get_payment_requestGet a payment request by id: status (Open/Completed/Cancelled/Expired), pay path, offered currencies, and the underlying draft once the payer committed.No findings

    Why it is in this group

    • The name "get_payment_request" says "get": a word for reading.
    Description, as the server wrote it
    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.
  • get_rateGet the current exchange rate for an asset in a fiat currency (rate = fiat units per 1 whole asset unit, with source provenance).No findings

    Why it is in this group

    • The name "get_rate" says "get": a word for reading.
    Description, as the server wrote it
    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.
  • get_transaction_templateGet 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 EV…No findings

    Why it is in this group

    • The name "get_transaction_template" says "get": a word for reading.
    Description, as the server wrote it
    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.
  • list_address_bookList the account's saved addresses (label, address, network, direction: Sending = recipients the owner pays, Receiving = the owner's own addresses).No findings

    Why it is in this group

    • The name "list_address_book" says "list": a word for reading.
    Description, as the server wrote it
    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.
  • list_draft_quotesList every quote (rate lock) of a fiat-priced draft, oldest first.No findings

    Why it is in this group

    • The name "list_draft_quotes" says "list": a word for reading.
    Description, as the server wrote it
    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.

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 1.5.0. Values in angle brackets are yours to fill in.

claude mcp add --transport http send21io https://send21.io/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json
{
  "permissions": {
    "allow": [
      "mcp__send21io__get_transaction_template",
      "mcp__send21io__get_fee_schedule",
      "mcp__send21io__get_account_status",
      "mcp__send21io__list_address_book",
      "mcp__send21io__get_draft",
      "mcp__send21io__get_payment_request",
      "mcp__send21io__get_rate",
      "mcp__send21io__list_draft_quotes",
      "mcp__send21io__get_draft_status"
    ],
    "ask": [
      "mcp__send21io__create_payment_request",
      "mcp__send21io__propose_receiving_address",
      "mcp__send21io__submit_lightning_proof",
      "mcp__send21io__create_account",
      "mcp__send21io__create_draft"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as send21io. Review it before you use it.