4byte
Get function signatures for the given selector from 4byte.directory
LABSCO SUMMARY
The Cast toolbox, callable mid-conversation.
Debugging a failed transaction usually means pasting hex between four websites. Here the selector lookup, the ABI decode, the balance check and the static call are all reachable from one place, on whichever EVM chain the contract lives.
What it is
A set of Ethereum developer tools exposed over MCP — Cast-style encode and decode operations, a multi-threaded vanity address generator, and RPC access to any EVM-compatible chain.
What you get
- Unknown calldata identified against 4byte.directory, then decoded into its parameters
- ABI encoding and decoding both ways, including a complete function call encoded with its selector
- Function selectors, event selectors and keccak256 hashes computed directly
- Vanity addresses generated to a prefix and a suffix, across up to 16 worker threads, with case sensitivity optional
- Ethereum addresses validated before you send anything to them
- Read-only static calls and balance queries, and transactions sent when you supply a private key — on any of the chains it lists
Requirements
Node — npm install, npm run build, npm start. The read tools need only an RPC endpoint for the chain. Sending a transaction requires a private key, and it is the one operation here that moves funds.
Setup effort
One command — npx blockchain-mcp-server
USE CASES
01
Working out what a transaction was actually calling
Look the selector up against 4byte.directory, then decode the calldata into readable parameters.
02
Building a call by hand
Encode the parameters, or the whole call with its selector, and check the selector is the one you expected.
03
Reading contract state without spending gas
A static call against the chain you name returns what the contract says, with no transaction and no signature.
04
Checking an address before you send to it
Validate the format, then read the balance — the two checks that catch most expensive mistakes.
05
Getting an address that starts with what you want
Generate to a prefix and a suffix across several worker threads, with case sensitivity on or off.
06
Matching a log to its event
Compute the event selector and the keccak256 hash, and compare against the topic you are holding.
14 tools
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
4byte-decode
Decode ABI-encoded calldata using 4byte.directory
abi-decode
decode abi encoded data
abi-encode
encode function parameters with abi
abi-encode-with-signature
encode function call with abi
event-sig
get event selector
generate-vanity-address
Generate Ethereum addresses matching specified prefix and suffix patterns with concurrent computation
get-balance
Get the balance of an address on any EVM-compatible chain
keccak256
calculate keccak256 hash
list-chains
List all supported EVM-compatible chains and their configurations
send-transaction
Send a transaction to a smart contract on any EVM-compatible chain (requires private key)
sig
get function selector
static-call
Make a static call to a smart contract on any EVM-compatible chain (read-only)
validate-ethereum-address
Validate the validity of an Ethereum address
BEFORE YOU INSTALL
What to know first
Tools you get
14 tools when we connected.
Requires
npx on PATH
CONTEXT COST
Light Standing cost
Rated by the size of the 14 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Connect your client
Add the block to your client, or run the command directly.
Server setup
Configuration file
JSON
{
"mcpServers": {
"blockchain-mcp-server": {
"command": "npx",
"args": [
"blockchain-mcp-server"
]
}
}
}npx
TERMINAL
npx blockchain-mcp-server
