arbitrum-cli: agent-first Arbitrum from one Rust binary

The gap

Every blockchain CLI today is either a heavyweight toolkit (Foundry) or a chain-specific SDK bundle that assumes a human reading the output. Neither is built for AI agents or automation pipelines that need to plumb chain data through other tools. We kept hitting the same friction: every new agent prototype began with re-wrapping cast or web3.py in something that emitted clean JSON.

What arbitrum-cli is

A single Rust binary that wraps Arbitrum RPC behind a clean surface. Three properties make it agent-first:

• JSON by default. Every command emits structured JSON so you can pipe directly to jq, feed it to an LLM, or hand it off to the next tool. --human when you want colored output for debugging.
• Generic exec. Any RPC method, any params, no waiting for us to add a wrapper. arbitrum-cli exec eth_getLogs --params '[{"fromBlock":"latest","address":"0x..."}]'
• MCP server built in. arbitrum-cli mcp exposes every command as a Model Context Protocol tool — Claude, Cursor, or any MCP-compatible agent can call Arbitrum directly with no glue code.

Why Rust, why one binary

Distribution is half the value of a CLI. cargo install arbitrum-cli is one command and one binary — no Python venv, no npm install, no version-pin gymnastics. For agent operators dropping this onto a fleet of ephemeral machines, that matters.

Part of a suite

arbitrum-cli is the first in a planned agent-first chain-tools suite from kcolbchain:

• arbitrum-cli — Arbitrum chain access
• superchain-trace — OP Superchain cross-chain message debugger
• stylus-profiler — Arbitrum Stylus WASM binary analyzer
• gas-oracle — L2 gas prediction from blob fee dynamics

All four follow the same conventions: JSON output, MCP tool exposure, single binary, no required services.