crypto-wallet

name	crypto-wallet
description	Check cryptocurrency wallet balances, token holdings, transaction history, token approvals, ENS name resolution, and on-chain activity. Use when asked about wallet balance, what tokens an address holds, transaction history, pending transactions, token allowances, ENS lookup, or address portfolio.

Crypto Wallet

Query on-chain wallet data: balances, tokens, transactions, approvals, and ENS resolution.

Common ERC-20 Function Selectors

Function	Selector	Params
balanceOf(address)	0x70a08231	address (32 bytes, left-padded)
allowance(address,address)	0xdd62ed3e	owner + spender (each 32 bytes)
decimals()	0x313ce567	none
symbol()	0x95d89b41	none
name()	0x06fdde03	none
totalSupply()	0x18160ddd	none

APIs

ETH Balance via Public RPC

Native ETH balance (eth_getBalance):

exec command="curl -s -X POST https://eth.llamarpc.com -H 'Content-Type: application/json' -d '{\"jsonrpc\":\"2.0\",\"method\":\"eth_getBalance\",\"params\":[\"0xADDRESS\",\"latest\"],\"id\":1}'"

ERC-20 token balance (eth_call with balanceOf):

exec command="curl -s -X POST https://eth.llamarpc.com -H 'Content-Type: application/json' -d '{\"jsonrpc\":\"2.0\",\"method\":\"eth_call\",\"params\":[{\"to\":\"0xTOKEN_CONTRACT\",\"data\":\"0x70a08231000000000000000000000000WALLET_NO_0x\"},\"latest\"],\"id\":1}'"

Result is hex. Convert: parseInt(result, 16) / 10^decimals

Multi-chain Public RPCs

Chain	RPC URL
Ethereum	https://eth.llamarpc.com
Arbitrum	https://arb1.arbitrum.io/rpc
Optimism	https://mainnet.optimism.io
Base	https://mainnet.base.org
Polygon	https://polygon-rpc.com
BSC	https://bsc-dataseed.binance.org
Avalanche	https://api.avax.network/ext/bc/C/rpc

Etherscan / Block Explorers (Free tier, API key optional)

Base URLs:

• Ethereum: https://api.etherscan.io/api
• Arbitrum: https://api.arbiscan.io/api
• Base: https://api.basescan.org/api
• Optimism: https://api-optimistic.etherscan.io/api
• Polygon: https://api.polygonscan.com/api
• BSC: https://api.bscscan.com/api

Token balances for address (requires free API key):

web_fetch url="https://api.etherscan.io/api?module=account&action=tokentx&address=0xADDRESS&page=1&offset=50&sort=desc&apikey=YOUR_KEY"

Normal transactions:

web_fetch url="https://api.etherscan.io/api?module=account&action=txlist&address=0xADDRESS&startblock=0&endblock=99999999&page=1&offset=20&sort=desc&apikey=YOUR_KEY"

ETH balance (no key needed, rate limited):

web_fetch url="https://api.etherscan.io/api?module=account&action=balance&address=0xADDRESS&tag=latest"

ENS Resolution

Forward (name to address) via RPC:

exec command="curl -s -X POST https://eth.llamarpc.com -H 'Content-Type: application/json' -d '{\"jsonrpc\":\"2.0\",\"method\":\"eth_call\",\"params\":[{\"to\":\"0x4976fb03C32e5B8cfe2b6cCB31c09Ba78EBaBa41\",\"data\":\"0x3b3b57de{NAMEHASH}\"},\"latest\"],\"id\":1}'"

Simpler: use ENS public API:

web_fetch url="https://ensdata.net/ADDRESS_OR_NAME"

Token Approvals

Check allowance (how much a spender can use):

exec command="curl -s -X POST https://eth.llamarpc.com -H 'Content-Type: application/json' -d '{\"jsonrpc\":\"2.0\",\"method\":\"eth_call\",\"params\":[{\"to\":\"0xTOKEN\",\"data\":\"0xdd62ed3e000000000000000000000000OWNER_NO_0x000000000000000000000000SPENDER_NO_0x\"},\"latest\"],\"id\":1}'"

Unlimited approval = 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff

External Tools (Optional)

• EVM MCP Server: npx @mcpdotdirect/evm-mcp-server — read balances, tokens, NFTs across 60+ EVM chains
• Base MCP: github.com/base/base-mcp — Coinbase-official Base chain tools

Usage Tips

• Always pad addresses to 32 bytes (64 hex chars) in eth_call data fields
• Strip 0x prefix from address when embedding in calldata, then left-pad with zeros
• Results from eth_call are hex-encoded; parse with parseInt(hex, 16)
• For ERC-20 balances, divide by 10^decimals (USDC=6, most tokens=18)
• For multi-token portfolios, use Etherscan tokentx endpoint rather than individual RPC calls
• Verify chain before querying — same address can exist on multiple chains with different balances