Every change Wellknown observed on this MCP server, newest first, with what it was before and what it became. Tool-surface changes carry the definition diff. Nothing here is edited after the fact.
https://send21.io/mcp/oauth (mcp_streamable_http) — from mcp_registry
Authorization not required, issuer https://send21.io
Changed the definition of "create_account", "create_draft", "create_payment_request" and 11 more
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Create send21 account for ownerbefore
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{"destructiveHint":false,"idempotentHint":false,"openWorldHint":true,"readOnlyHint":false,"title":"Create send21 account for owner"}before
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Create payment draftbefore
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{"destructiveHint":false,"idempotentHint":false,"openWorldHint":false,"readOnlyHint":false,"title":"Create payment draft"}before
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Create pay linkbefore
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{"destructiveHint":false,"idempotentHint":false,"openWorldHint":false,"readOnlyHint":false,"title":"Create pay link"}before
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Get account statusbefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"Get account status"}before
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Get payment draftbefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"Get payment draft"}before
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Get draft statusbefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"Get draft status"}before
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Get fee schedulebefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"Get fee schedule"}before
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Get pay linkbefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"Get pay link"}before
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Get exchange ratebefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"Get exchange rate"}before
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Get wallet payment instructionsbefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"Get wallet payment instructions"}before
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List address bookbefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"List address book"}before
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List draft quotesbefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":true,"title":"List draft quotes"}before
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Propose receiving addressbefore
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{"destructiveHint":false,"idempotentHint":false,"openWorldHint":false,"readOnlyHint":false,"title":"Propose receiving address"}before
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Submit Lightning payment proofbefore
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{"destructiveHint":false,"idempotentHint":true,"openWorldHint":false,"readOnlyHint":false,"title":"Submit Lightning payment proof"}Added "create_account", "get_account_status" and "propose_receiving_address"; changed the definition of "create_draft" and "create_payment_request" (11 tools before, 14 now)
⟨61 unchanged words⟩ 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.
⟨41 unchanged words⟩ 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.
Certificate changed, valid to 2027-01-06
Changed the definition of "create_draft" and "create_payment_request"
{"properties":{"amountBaseUnits":{"default":null,"description":"Exact amount in base units (sats ⟨13 unchanged words⟩ "integer","null"]},"currency":{"default":null,"description":"Asset: Btc (default), Usdc, ⟨16 unchanged words⟩ "string","null"]},"fiatAmount":{"default":null,"description":"Fiat amount; requires fiatCurrency","type":["number","null"]},"fiatCurrency":{"default":null,"description":"Fiat currency code for fiat-pegged amount, ⟨3 unchanged words⟩ "string","null"]},"idempotencyKey":{"default":null,"description":"Idempotency key.RetriesA retry with the same keyreturnand the same parameters returns the original
Changed the definition of "create_payment_request" and "get_draft_status"
⟨231 unchanged words⟩ "type":["string","null"]},"reuseOpenForOrder":{"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. Recommended for agents that may retry with a new idempotency key.","type":["boolean","null"]},"shortfallAbsorbUpToPercent":{"default":null,"description":"Accept ⟨48 unchanged words⟩
⟨5 unchanged words⟩ draft: status (AwaitingPayment/Seen/Confirmed/Expired/Cancelled), paying txid,confirmations.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).
Added "list_draft_quotes"; changed the definition of "create_draft", "create_payment_request" and "get_payment_request" (10 tools before, 11 now)
⟨133 unchanged words⟩ Arbitrum and Polygon)","type":"string"},"shortfallAbsorbUpToPercent":{"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.","type":["number","null"]}},"required":["receiverAddress","network"," ⟨8 unchanged words⟩
{"properties":{"declineNote":{"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.\"","type":["string","null"]},"Added "submit_lightning_proof" (9 tools before, 10 now)
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.
Changed the definition of "create_payment_request", "get_rate" and "get_transaction_template"
Only numbers and dates differ: this server embeds live figures in the definition, so the text moves without the contract changing.
⟨13 unchanged words⟩ to get paid). Price in any of165161 fiat currencies; the payer opens the returned payPath ⟨23 unchanged words⟩
⟨27 unchanged words⟩ , Usdc, Usdt, Eurc, Sol, Eth.165161ISO-4217ISO 4217
Changed the definition of "create_draft", "create_payment_request" and "get_rate"
⟨19 unchanged words⟩ units (sats for BTC, micro-units for stablecoins, lamports for SOL, gwei for ETH) via amountBaseUnits, or fiat-pegged via fiatCurrency+fiatAmount with ⟨34 unchanged words⟩
⟨3 unchanged words⟩ Exact amount in base units (sats / micro-units / lamports / gwei); omit when using fiat pricing","type ⟨4 unchanged words⟩ Asset: Btc (default), Usdc, Usdt, Eurc, Sol (native SOL on Solana), orEurcEth (native ETH on Ethereum, Base, Arbitrum)","type":["string","null"]} ⟨54 unchanged words⟩ ":"Network: Mainnet, Solana, Ethereum, Base,
Changed the definition of "create_draft"
⟨100 unchanged words⟩ receiverAddress":{"description":"Receiver address (Bitcoinbc1…bc1..., Solana base58, or0x…0x... for Ethereum/Base)","type":"string"}} ⟨11 unchanged words⟩
Changed the definition of "create_draft", "create_payment_request" and "get_transaction_template"
⟨50 unchanged words⟩ only when the sender signs in their ownwallet —wallet. send21 never holds keys. Requires scope drafts:write.
⟨54 unchanged words⟩ "]},"idempotencyKey":{"description":"Idempotencykey —key.retriesRetries with the same key return the original draft ⟨58 unchanged words⟩
Certificate recorded, valid to 2026-11-07
Authorization not required
First tool surface recorded: 9 tools (server version 1.0.0.0)
Showing the latest 16 events. The API returns up to 500 and filters by kind: ?kind=tool_surface_changed
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 a…
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.
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.
⟨60 unchanged words⟩ "string","null"]},"expiryHours":{"default":null,"description":"Hours until the request expires (default ⟨26 unchanged words⟩ ,"type":"string"},"idempotencyKey":{"default":null,"description":"Idempotency key.RetriesA retry with the same keyreturnand the same parameters returns the originalrequestrequest; the same key with another amount, currency or address is refused (422) and creates nothing","type":["string","null"]},"memo":{"default":null,"description":"Message shown to the payer (max ⟨96 unchanged words⟩ ,"type":"array"},"orderId":{"default":null,"description":"Your own order/reference id, echoed in ⟨25 unchanged words⟩ creating a second pay link for the sameorder.order (only when it asks for the same amount, currency and addresses). Recommended for agents that may retry with a ⟨49 unchanged words⟩ ,"required":["fiatCurrency","fiatAmount","options","orderId","memo","expiryHours","idempotencyKey"],"type":"object"}
⟨12 unchanged words⟩ 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.
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.
Get themulti-outputtransaction template foraan on-chain draft:BitcoineveryCoreoutput to pay, plus walletcreatefundedpsbt arguments andElectrum/Sparrowa pay-to-manyCSV.CSV on Bitcoin, or payment URIs (and calldata on EVM chains) on Solana, Ethereum, Base, Arbitrum and Polygon. Theoperator'ssender's own wallet funds, reviews,and signsit.it; send21 contains no signing code. Not for Lightning drafts (pay their invoice). Requires scope drafts:read.
⟨82 unchanged words⟩ description":"The RECEIVER's own address for thiscurrencycurrency; for Lightning, the receiver's Lightning address (name@wallet.com)","type":"string"},"currency":{"description":"Asset: Btc, Usdc, Usdt, Eurc, Sol, orEurcEth","type":"string"},"method":{"default":null,"description":"MultiOutput (on-chain, default) or Lightning (Btc on Mainnet; send21 confirms it when the receiver's provider supports LUD-21)","type":["string","null"]},"network":{"description":"Network the address lives on: Mainnet, Solana, Ethereum, Base, Arbitrum, orBasePolygon","type":"string"}},"required": ⟨31 unchanged words⟩
⟨23 unchanged words⟩ provenance). Assets: Btc, Usdc, Usdt,Eurc.Eurc, Sol, Eth. 165 ISO-4217 fiat currencies are supported. Requires an API key.
⟨2 unchanged words⟩ description":"Asset: Btc, Usdc, Usdt, Eurc, Sol, orEurcEth","type":"string"},"fiatCurrency":{ ⟨15 unchanged words⟩
⟨36 unchanged words⟩ string"},"idempotencyKey":{"description":"Idempotencykey —key.retriesRetries with the same key return the original request ⟨74 unchanged words⟩ orderId":{"description":"Your own order/reference id—, echoed in webhooks for reconciliation","type": ⟨12 unchanged words⟩
⟨16 unchanged words⟩ The operator's wallet funds, reviews, and signsit —it. send21 contains no signing code. Requires scope drafts:read.