arbitrum-cli

Agent-first Arbitrum CLI

JSON in, JSON out. MCP-compatible. Single Rust binary. Built for LLMs, automation pipelines, and developers who think in JSON.

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Quick Start · Commands · Agent mode · MCP

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Why

Every blockchain CLI today is either a heavyweight toolkit (Foundry) or a chain-specific SDK bundle. Neither is built for agents. arbitrum-cli wraps Arbitrum RPC behind a clean surface that:

• Emits JSON by default so agents can pipe output anywhere
• Has a generic exec command for any RPC method
• Exposes tools via MCP so Claude, Cursor, or any AI agent can call it natively
• Ships as a single Rust binary — cargo install arbitrum-cli and go

Part of the agent-first blockchain CLI suite by kcolbchain.

Quick start

cargo install arbitrum-cli

# Query the latest block (JSON output, agent-ready)
arbitrum-cli block latest

# Check an address balance
arbitrum-cli balance 0xC75020d5f669F5D15Afcb81b0e5F6d21bCDa9664

# Check a token balance (USDC on Arbitrum)
arbitrum-cli token \
  0xaf88d065e77c8cC2239327C5EDb3A432268e5831 \
  0xC75020d5f669F5D15Afcb81b0e5F6d21bCDa9664

# Get current gas price
arbitrum-cli gas

# Human-readable output
arbitrum-cli block latest --human

Commands

Command	What it does
block <number|latest>	Fetch block info
tx <hash>	Fetch transaction by hash
balance <address>	Native ETH balance
token <token> <address>	ERC-20 balance with decimals
call --data <hex> <to>	Read contract via eth_call
gas	Current gas price + block number
watch blocks	Stream new blocks (polling)
exec <method> --params '[...]'	Generic RPC passthrough
mcp	Start MCP server for AI agents
info	List supported Arbitrum chains

Agent mode

All commands default to JSON output. No flags, no ceremony — pipe it into jq, feed it to an LLM, or forward to any tool.

# Agent-friendly
arbitrum-cli balance 0xC750... | jq .balance_eth

# Generic RPC for agents — any method, any params
arbitrum-cli exec eth_chainId --params '[]'
arbitrum-cli exec eth_getLogs --params '[{"fromBlock":"latest","address":"0x..."}]'

Use --human for colored terminal output when you're debugging.

MCP server

Expose arbitrum-cli as a Model Context Protocol server so Claude, Cursor, or any MCP-compatible agent can call Arbitrum directly.

arbitrum-cli mcp --bind 127.0.0.1:3456

Tools exposed:

• arbitrum.block · arbitrum.tx · arbitrum.balance · arbitrum.token
• arbitrum.call · arbitrum.gas · arbitrum.exec

(MCP integration is stubbed in v0.1 — full stdio + SSE support in v0.2.)

Configuration

# Use a custom RPC (env var)
export ARBITRUM_RPC_URL=https://arb-mainnet.g.alchemy.com/v2/YOUR_KEY
arbitrum-cli block latest

# Or pass inline
arbitrum-cli --rpc https://arb1.arbitrum.io/rpc gas

Default RPC: https://arb1.arbitrum.io/rpc (Arbitrum One)

Part of the kcolbchain agent-first suite

Tool	Purpose
arbitrum-cli	Arbitrum chain access
superchain-trace	OP Superchain cross-chain message debugger
stylus-profiler	Arbitrum Stylus WASM binary analyzer
gas-oracle	L2 gas cost prediction via blob fees

License

MIT — do whatever you want. Attribution appreciated.

Contributing

See kcolbchain.com/join. Good first issues welcome.