Vultisig MCP Server

An MCP server that exposes Vultisig vault operations, multi-chain balance queries, transaction building, and DeFi protocol interactions to LLM-powered agents. Supports both stdio and HTTP transports.

Quick Start

# Build
go build -o mcp-server ./cmd/mcp-server/

# Run over stdio (default)
./mcp-server

# Run over HTTP on port 8080
./mcp-server -http :8080

Environment Variables

Variable	Default	Description
`EVM_ETHEREUM_URL`	`https://ethereum-rpc.publicnode.com`	Ethereum JSON-RPC endpoint
`EVM_BSC_URL`	`https://bsc-rpc.publicnode.com`	BNB Smart Chain JSON-RPC endpoint
`EVM_POLYGON_URL`	`https://polygon-bor-rpc.publicnode.com`	Polygon JSON-RPC endpoint
`EVM_AVALANCHE_URL`	`https://avalanche-c-chain-rpc.publicnode.com`	Avalanche C-Chain JSON-RPC endpoint
`EVM_ARBITRUM_URL`	`https://arbitrum-one-rpc.publicnode.com`	Arbitrum One JSON-RPC endpoint
`EVM_OPTIMISM_URL`	`https://optimism-rpc.publicnode.com`	Optimism JSON-RPC endpoint
`EVM_BASE_URL`	`https://base-rpc.publicnode.com`	Base JSON-RPC endpoint
`EVM_BLAST_URL`	`https://blast-rpc.publicnode.com`	Blast JSON-RPC endpoint
`EVM_MANTLE_URL`	`https://mantle-rpc.publicnode.com`	Mantle JSON-RPC endpoint
`EVM_ZKSYNC_URL`	`https://mainnet.era.zksync.io`	zkSync Era JSON-RPC endpoint
`COINGECKO_API_KEY`	(empty)	CoinGecko API key (optional, raises rate limits)
`BLOCKCHAIR_API_URL`	`https://api.vultisig.com/blockchair`	Blockchair proxy base URL for UTXO chain queries
`THORCHAIN_URL`	`https://thornode.ninerealms.com`	THORChain node URL for fee rates and swap data

Tools

Vault

`set_vault_info`

Store vault key material for the current session. Must be called before any vault-derived address or balance queries.

Parameter	Required	Description
`ecdsa_public_key`	Yes	Hex-encoded compressed ECDSA public key (33 bytes / 66 hex chars)
`eddsa_public_key`	Yes	Hex-encoded EdDSA public key (32 bytes / 64 hex chars)
`chain_code`	Yes	Hex-encoded 32-byte chain code for BIP-32 derivation

`get_address`

Derive the address for a given blockchain network from vault key material. Requires set_vault_info first.

Parameter	Required	Description
`chain`	Yes	Blockchain network name (see supported chains below)

Supported chains: Arbitrum, Avalanche, Base, Bitcoin, Bitcoin-Cash, Blast, BSC, Cosmos, CronosChain, Dash, Dogecoin, Dydx, Ethereum, Kujira, Litecoin, Mantle, MayaChain, Noble, Optimism, Osmosis, Polygon, Ripple, Solana, Sui, Terra, TerraClassic, THORChain, Tron, Zcash, Zksync.

Token Discovery

`search_token`

Search for tokens by ticker symbol, name, or contract address via CoinGecko. Returns token metadata and all known contract deployments across chains, ranked by market cap.

Parameter	Required	Description
`query`	Yes	Ticker (e.g. `USDC`), name (e.g. `Uniswap`), or contract address

EVM (multi-chain)

All EVM tools accept a chain parameter (default: Ethereum). Supported chains: Ethereum, BSC, Polygon, Avalanche, Arbitrum, Optimism, Base, Blast, Mantle, Zksync.

`evm_get_balance`

Query the native coin balance of an address. Address falls back to vault-derived if omitted.

Parameter	Required	Description
`chain`	No	EVM chain name (default: `Ethereum`)
`address`	No	Wallet address. Falls back to vault-derived if omitted.

`evm_get_token_balance`

Query an ERC-20 token balance. Returns symbol, balance, and decimals.

Parameter	Required	Description
`chain`	No	EVM chain name (default: `Ethereum`)
`contract_address`	Yes	ERC-20 token contract address (0x-prefixed)
`address`	No	Holder address. Falls back to vault-derived if omitted.

`evm_check_allowance`

Check how much of an ERC-20 token a spender is allowed to transfer. Used to determine if an approve transaction is needed before a swap or protocol interaction.

Parameter	Required	Description
`chain`	No	EVM chain name (default: `Ethereum`)
`contract_address`	Yes	ERC-20 token contract address (0x-prefixed)
`owner`	No	Token holder address. Falls back to vault-derived if omitted.
`spender`	Yes	Address allowed to spend tokens (e.g. DEX router contract)

`evm_tx_info`

Get nonce, gas prices, and chain ID for building an EVM transaction. Optionally estimates gas if to/data/value are provided.

Parameter	Required	Description
`chain`	No	EVM chain name (default: `Ethereum`)
`address`	No	Sender address. Falls back to vault-derived if omitted.
`to`	No	Destination address for gas estimation
`data`	No	Hex calldata for gas estimation
`value`	No	Wei value for gas estimation (decimal string)

`evm_call`

Execute a read-only eth_call against a contract. Returns raw hex output and optionally decodes it.

Parameter	Required	Description
`chain`	No	EVM chain name (default: `Ethereum`)
`to`	Yes	Contract address (0x-prefixed)
`data`	Yes	Hex-encoded calldata (0x-prefixed)
`from`	No	Sender address for call context
`value`	No	Wei value to send with the call (decimal string)
`block`	No	Block number (decimal) or `"latest"` (default)
`output_types`	No	Comma-separated ABI types to decode output (e.g. `"uint256,address"`)

`build_evm_tx`

Build an unsigned EIP-1559 (type 2) transaction for any EVM chain. Obtain fee/nonce parameters from evm_tx_info first.

Parameter	Required	Description
`chain`	No	EVM chain name (default: `Ethereum`). Sets `chain_id` when not explicitly overridden.
`to`	Yes	Destination address (0x-prefixed)
`value`	Yes	Wei value to transfer (decimal string)
`nonce`	Yes	Sender nonce (decimal string)
`gas_limit`	Yes	Gas limit (decimal string)
`max_fee_per_gas`	Yes	Max fee per gas in wei (decimal string)
`max_priority_fee_per_gas`	Yes	Max priority fee (tip) per gas in wei (decimal string)
`data`	No	Hex-encoded calldata (default `"0x"`)
`chain_id`	No	Chain ID override (decimal string)

Swaps

`build_swap_tx`

Build unsigned transaction(s) for a token swap. Supports THORChain, MayaChain, 1inch, LiFi, Jupiter, and Uniswap. Returns the swap transaction and an optional ERC-20 approval transaction.

Parameter	Required	Description
`from_chain`	Yes	Source chain (e.g. `"Ethereum"`, `"Bitcoin"`)
`from_symbol`	Yes	Source token symbol (e.g. `"ETH"`, `"USDC"`)
`from_address`	No	Source token contract address (empty for native coins)
`from_decimals`	Yes	Source token decimals (e.g. `18` for ETH, `6` for USDC)
`to_chain`	Yes	Destination chain
`to_symbol`	Yes	Destination token symbol
`to_address`	No	Destination token contract address (empty for native coins)
`to_decimals`	Yes	Destination token decimals
`amount`	Yes	Amount in base units (e.g. `"1000000"` for 1 USDC)
`sender`	Yes	Sender wallet address
`destination`	Yes	Destination wallet address

UTXO Chains

UTXO tools support: Bitcoin, Bitcoin-Cash, Dash, Dogecoin, Litecoin, Zcash.

`get_utxo_balance`

Query balance and address stats. Address falls back to vault-derived if omitted.

Parameter	Required	Description
`chain`	Yes	UTXO chain name
`address`	No	Address to query. Falls back to vault-derived if omitted.

`get_utxo_transactions`

List recent transaction hashes for an address.

Parameter	Required	Description
`chain`	Yes	UTXO chain name
`address`	No	Address to query. Falls back to vault-derived if omitted.
`limit`	No	Max number of hashes to return (default 50, max 100)

`list_utxos`

List unspent transaction outputs for an address.

Parameter	Required	Description
`chain`	Yes	UTXO chain name
`address`	No	Address to query. Falls back to vault-derived if omitted.

`build_utxo_tx`

Build an unsigned UTXO transaction with explicit inputs and outputs. Fee = sum(inputs) − sum(outputs).

Parameter	Required	Description
`chain`	Yes	UTXO chain name
`inputs`	Yes	JSON array: `[{"txid":"<hex>","vout":<n>,"value":<sats>}]`
`outputs`	Yes	JSON array: `[{"address":"<addr>","amount":<sats>}]`

Bitcoin (high-level)

`btc_fee_rate`

Get the recommended Bitcoin fee rate in sat/vB from THORChain inbound addresses. No parameters.

`build_btc_send`

Build an unsigned Bitcoin PSBT for a send or swap. Automatically selects UTXOs, calculates fees, and handles change. Requires set_vault_info first.

Parameter	Required	Description
`to_address`	Yes	Recipient Bitcoin address (or THORChain vault address for swaps)
`amount`	Yes	Amount to send in satoshis (decimal string)
`fee_rate`	Yes	Fee rate in sat/vB (use `btc_fee_rate` tool to get recommended rate)
`memo`	No	OP_RETURN memo (e.g. THORChain swap instruction). Adds an OP_RETURN output.
`address`	No	Sender Bitcoin address. Falls back to vault-derived if omitted.

Encoding / Utilities

`abi_encode`

ABI-encode a Solidity function call or pack raw arguments. Handles 4-byte selector prepending for function calls.

Parameter	Required	Description
`signature`	Yes	Function signature (e.g. `"transfer(address,uint256)"`) or bare types (e.g. `"uint256,address"`)
`args`	Yes	Array of argument values as strings (addresses as `0x`-hex, integers as decimal)

`abi_decode`

ABI-decode hex-encoded calldata or return data.

Parameter	Required	Description
`signature`	Yes	Function signature or bare types string
`data`	Yes	Hex-encoded data to decode (0x-prefixed)

`convert_amount`

Convert between human-readable and base unit amounts.

Parameter	Required	Description
`amount`	Yes	Amount to convert
`decimals`	Yes	Number of decimal places (e.g. `18` for ETH, `6` for USDC)
`direction`	Yes	`"to_base"` (human→base) or `"to_human"` (base→human)

Aave V3 (Ethereum)

Aave V3 tools operate on Ethereum mainnet only.

`aave_v3_deposit`

Build unsigned transactions to deposit (supply) tokens into Aave V3. Returns an approve tx and a supply tx.

Parameter	Required	Description
`asset`	Yes	ERC-20 token contract address (0x-prefixed)
`amount`	Yes	Amount in human-readable units (e.g. `"100.5"`) or `"max"` for full balance
`address`	No	Depositor's Ethereum address. Falls back to vault-derived if omitted.

`aave_v3_withdraw`

Build an unsigned transaction to withdraw tokens from Aave V3.

Parameter	Required	Description
`asset`	Yes	ERC-20 token contract address (0x-prefixed)
`amount`	Yes	Amount in human-readable units or `"max"` for full withdrawal
`address`	No	Withdrawer's Ethereum address. Falls back to vault-derived if omitted.

`aave_v3_borrow`

Build an unsigned transaction to borrow tokens from Aave V3 at variable rate.

Parameter	Required	Description
`asset`	Yes	ERC-20 token contract address (0x-prefixed)
`amount`	Yes	Amount in human-readable units
`address`	No	Borrower's Ethereum address. Falls back to vault-derived if omitted.

`aave_v3_repay`

Build unsigned transactions to repay a borrow on Aave V3. Returns an approve tx and a repay tx.

Parameter	Required	Description
`asset`	Yes	ERC-20 token contract address (0x-prefixed)
`amount`	Yes	Amount in human-readable units or `"max"` to repay entire debt
`address`	No	Repayer's Ethereum address. Falls back to vault-derived if omitted.

`aave_v3_get_balances`

Query Aave V3 account summary: total collateral, debt, available borrows (USD), LTV, and health factor.

Parameter	Required	Description
`address`	No	Ethereum address. Falls back to vault-derived if omitted.

`aave_v3_get_rates`

Query Aave V3 supply APY, variable borrow APY, and reserve configuration for a token.

Parameter	Required	Description
`asset`	Yes	ERC-20 token contract address (0x-prefixed)

MCP Client Configuration

Stdio (default)

{
  "mcpServers": {
    "vultisig": {
      "command": "/path/to/mcp-server",
      "env": {
        "EVM_ETHEREUM_URL": "https://ethereum-rpc.publicnode.com"
      }
    }
  }
}

HTTP

# Start the server
./mcp-server -http :8080

# MCP endpoint: POST/GET/DELETE http://localhost:8080/mcp

{
  "mcpServers": {
    "vultisig": {
      "url": "http://localhost:8080/mcp"
    }
  }
}

Name		Name	Last commit message	Last commit date
Latest commit History 48 Commits
.github/workflows		.github/workflows
cmd/mcp-server		cmd/mcp-server
internal		internal
scripts		scripts
.env.example		.env.example
.gitignore		.gitignore
CLAUDE.md		CLAUDE.md
README.md		README.md
flake.lock		flake.lock
flake.nix		flake.nix
go.mod		go.mod
go.sum		go.sum
main.go		main.go

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Vultisig MCP Server

Quick Start

Environment Variables

Tools

Vault

set_vault_info

get_address

Token Discovery

search_token

EVM (multi-chain)

evm_get_balance

evm_get_token_balance

evm_check_allowance

evm_tx_info

evm_call

build_evm_tx

Swaps

build_swap_tx

UTXO Chains

get_utxo_balance

get_utxo_transactions

list_utxos

build_utxo_tx

Bitcoin (high-level)

btc_fee_rate

build_btc_send

Encoding / Utilities

abi_encode

abi_decode

convert_amount

Aave V3 (Ethereum)

aave_v3_deposit

aave_v3_withdraw

aave_v3_borrow

aave_v3_repay

aave_v3_get_balances

aave_v3_get_rates