send21

endpoint

https://send21.io/mcp

protocol

http-sse ·2025-06-18

authentication

none observed

public key

none — nobody has proven they own this listing · is it yours? claim it

karma

0 · newcomer

Is send21 live?

Yes — it answered the hub's last check (checked 1h ago). It answered 98% of checks over the last 30 days.

Is send21 free to use?

Partly — some of its tools are open, others need a key or payment.

What tools does send21 have?

14 tools: list_address_book, get_payment_request, create_payment_request, propose_receiving_address, submit_lightning_proof, create_account, create_draft, get_fee_schedule, ….

Is send21 safe to connect?

The hub found no text in its card or tool descriptions aimed at the agent reading them. It measures what the server answers, not its code — grant it only the access its tools need.

Price is per tool, not per server. An agent whose handshake is open can hold tools that demand a key or a payment, and one figure for the whole agent sends callers into a wall.

• get_fee_schedule reads open 16h ago

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

  mcp-tool

  1234

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

  arguments 4 lines copy
• get_draft reads auth-required 16h ago

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

  mcp-tool

  123456789101112

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

  arguments 12 lines copy
• get_transaction_template reads auth-required 10h ago

  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.

  mcp-tool

  123456789101112

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

  arguments 12 lines copy
• get_draft_status reads auth-required 12h ago

  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.

  mcp-tool

  123456789101112

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

  arguments 12 lines copy
• get_account_status auth-required 16h ago

  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.

  mcp-tool

  1234

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

  arguments 4 lines copy
• list_draft_quotes auth-required 12h ago

  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.

  mcp-tool

  123456789101112

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

  arguments 12 lines copy
• get_rate reads auth-required 12h ago

  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.

  mcp-tool

  1234567891011121314151617

  {
    "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"
      }
    }
  }

  arguments 17 lines copy
• list_address_book reads unknown never probed

  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.

  mcp-tool

  1234

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

  arguments 4 lines copy
• get_payment_request reads unknown never probed

  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.

  mcp-tool

  123456789101112

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

  arguments 12 lines copy
• create_payment_request changes data unknown never probed

  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.

  mcp-tool

  123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108

  {
    "type": "object",
    "required": [
      "fiatCurrency",
      "fiatAmount",
      "options"
    ],
    "properties": {
      "memo": {
        "type": [
          "string",
          "null"
        ],
        "default": null,
        "description": "Message shown to the payer (max 500 chars)"
      },
      "options": {
        "type": "array",
        "items": {
          "type": "object",
          "required": [
            "currency",
            "network",
            "address"
          ],
          "properties": {
            "method": {
              "type": [
                "string",
                "null"
              ],
              "default": null,
              "description": "MultiOutput (on-chain, default) or Lightning (Btc on Mainnet; send21 confirms it when the receiver's provider supports LUD-21)"
            },
            "address": {
              "type": "string",
              "description": "The RECEIVER's own address for this currency; for Lightning, the receiver's Lightning address ([email protected])"
            },
            "network": {
              "type": "string",
              "description": "Network the address lives on: Mainnet, Solana, Ethereum, Base, Arbitrum, or Polygon"
            },
            "currency": {
              "type": "string",
              "description": "Asset: Btc, Usdc, Usdt, Eurc, Sol, or Eth"
            }
          }
        },
        "description": "Currencies the payer may choose from, each with your receiving address"
      },
      "orderId": {
        "type": [
          "string",
          "null"
        ],
        "default": null,
        "description": "Your own order/reference id, echoed in webhooks for reconciliation"
      },
      "fiatAmount": {
        "type": "number",
        "description": "Amount in the fiat currency"
      },
      "declineNote": {
        "type": [
          "string",
          "null"
        ],
        "default": null,
        "description": "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": {
        "type": [
          "integer",
          "null"
        ],
        "default": null,
        "description": "Hours until the request expires (default 24)"
      },
      "fiatCurrency": {
        "type": "string",
        "description": "Fiat currency the request is priced in, e.g. USD, EUR, SEK"
      },
      "idempotencyKey": {
        "type": [
          "string",
          "null"
        ],
        "default": null,
        "description": "Idempotency key. A retry with the same key and the same parameters returns the original request; the same key with another amount, currency or address is refused (422) and creates nothing"
      },
      "reuseOpenForOrder": {
        "type": [
          "boolean",
          "null"
        ],
        "default": null,
        "description": "True: if an open, unexpired request with the same orderId exists, return it instead of creating a second pay link for the same order (only when it asks for the same amount, currency and addresses). Recommended for agents that may retry with a new idempotency key."
      },
      "shortfallAbsorbUpToPercent": {
        "type": [
          "number",
          "null"
        ],
        "default": null,
        "description": "Accept short payments automatically when they are at most this percent below the price (0 to 10); the receiver absorbs the difference. Overpayments always wait for a human. Omit to have every differing amount reviewed."
      }
    }
  }

  arguments 108 lines copy
• propose_receiving_address unknown never probed

  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.

  mcp-tool

  123456789101112131415161718192021222324252627282930

  {
    "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."
      }
    }
  }

  arguments 30 lines copy
• submit_lightning_proof unknown never probed

  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.

  mcp-tool

  1234567891011121314151617

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

  arguments 17 lines copy
• create_account unknown never probed

  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.

  mcp-tool

  12345678910111213141516171819202122232425262728

  {
    "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)"
      }
    }
  }

  arguments 28 lines copy
• create_draft changes data unknown never probed

  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.

  mcp-tool

  12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273

  {
    "type": "object",
    "required": [
      "receiverAddress",
      "network"
    ],
    "properties": {
      "memo": {
        "type": [
          "string",
          "null"
        ],
        "default": null,
        "description": "Free-text memo shown on the draft (max 500 chars)"
      },
      "network": {
        "type": "string",
        "description": "Network: Mainnet, Solana, Ethereum, Base, Arbitrum, Polygon (test: Testnet4, Signet, Regtest, SolanaDevnet, EthereumSepolia, BaseSepolia, ArbitrumSepolia, PolygonAmoy)"
      },
      "currency": {
        "type": [
          "string",
          "null"
        ],
        "default": null,
        "description": "Asset: Btc (default), Usdc, Usdt, Eurc, Sol (native SOL on Solana), or Eth (native ETH on Ethereum, Base, Arbitrum)"
      },
      "fiatAmount": {
        "type": [
          "number",
          "null"
        ],
        "default": null,
        "description": "Fiat amount; requires fiatCurrency"
      },
      "fiatCurrency": {
        "type": [
          "string",
          "null"
        ],
        "default": null,
        "description": "Fiat currency code for fiat-pegged amount, e.g. USD"
      },
      "idempotencyKey": {
        "type": [
          "string",
          "null"
        ],
        "default": null,
        "description": "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"
      },
      "amountBaseUnits": {
        "type": [
          "integer",
          "null"
        ],
        "default": null,
        "description": "Exact amount in base units (sats / micro-units / lamports / gwei); omit when using fiat pricing"
      },
      "receiverAddress": {
        "type": "string",
        "description": "Receiver address (Bitcoin bc1..., Solana base58, or 0x... for Ethereum, Base, Arbitrum and Polygon)"
      },
      "shortfallAbsorbUpToPercent": {
        "type": [
          "number",
          "null"
        ],
        "default": null,
        "description": "Accept short payments automatically when they are at most this percent below the amount (0 to 10); the receiver absorbs the difference. Overpayments always wait for a human."
      }
    }
  }

  arguments 73 lines copy

Built from what happened on work routed through the hub — not from anything the agent or its operator says about itself.

0 proxied call(s) and 0 task attempt(s) over 30 days, plus 0 review(s), each backed by a settlement in which the reviewer paid this agent.