Sign an EVM transaction or EIP-712 typed-data message. Three actions: (1) sign-unsigned-hex: sign pre-built unsigned tx hex; (2) sign-from-details: build and sign from fields (blockchain, network, toAddress, value, gas, fee, etc.); (3) sign-typed-data: sign an EIP-712 typed-data message — the x402 GASLESS path, e.g. the EIP-3009 TransferWithAuthorization returned by the x402 buyer /authorize (scheme eip712). For (3) pass domain/types/primaryType/message verbatim; it returns a 65-byte signature (no tx built). Network names (e.g. ethereum+sepolia, polygon+mainnet) are mapped to chainId internally. Private key is always passed as parameter (never from env). SECURITY: Private keys may be logged by MCP clients or stored in conversation history — use only in trusted local environments.

Sign a UTXO transaction (bitcoin, bitcoin-cash, litecoin, dogecoin, dash, zcash). Two actions: (1) sign-from-details: sign from prepared transaction object (e.g. HD wallet prepare-transaction); (2) sign-unsigned-hex: sign from raw unsigned tx hex (provide inputs metadata: script, satoshis per input). Private key is passed as parameter (never from env). SECURITY: Private keys may be logged by MCP clients or stored in conversation history — use only in trusted local environments.

Sign a Tron transaction (no TronWeb): Node crypto (sha256) + elliptic (secp256k1) + minimal protobuf encode/decode. Two actions: (1) sign-from-details: sign from transaction object (must include raw_data_hex); (2) sign-unsigned-hex: sign from raw unsigned tx hex. Returns signedTransactionHex. Private key is passed as parameter (never from env). SECURITY: Private keys may be logged by MCP clients or stored in conversation history — use only in trusted local environments.

Sign an XRP (Ripple) transaction. Two actions: (1) sign-from-details: sign from transaction object (JSON); (2) sign-unsigned-hex: sign from raw unsigned tx hex (XRPL serialized). Returns signedTransactionHex and signedTransactionHash. Secret is passed as parameter (never from env). SECURITY: Private keys may be logged by MCP clients or stored in conversation history — use only in trusted local environments.

Sign a Kaspa (native KAS) transaction locally. Kaspa is a UTXO/blockDAG chain (schnorr signatures, mainnet only). Action sign-from-details: sign from a prepared transaction object (data.item from the Kaspa prepare-transaction API) — each input carries its prevout script + sompi. Returns the signed tx as JSON (the form the Kaspa broadcast service expects). Private keys (one per input) are passed as parameters (never from env). SECURITY: Private keys may be logged by MCP clients or stored in conversation history — use only in trusted local environments.

Partial-sign a Solana (SVM) x402 payment transaction locally (@solana/web3.js). One action: partial-sign — deserialize the base64 UNSIGNED TransferChecked tx from the x402 buyer /authorize (scheme svm-transaction), add ONLY the source-authority (buyer) signature, and re-serialize to base64. The feePayer slot stays UNSIGNED — the facilitator signs it at settle. Returns { transaction } (base64). Secret key is base58, passed as parameter (never from env). SECURITY: keys may be logged by MCP clients or stored in conversation history — use only in trusted local environments.