Three steps. One API call. Zero capital at risk.
ArbiSim Guard spawns an ephemeral Anvil fork of any supported chain at the current block. Your transaction executes against the exact live state — real liquidity, real prices, real protocols.
The analytical engine parses execution traces, computes chain-specific gas, detects Stylus WASM contracts, validates ERC-4337 UserOps, checks ERC-8004 agent reputation, and scores MEV risk.
You receive an APPROVED or REJECTED verdict with a structured safety flag object, full gas breakdown, Timeboost recommendation, and the exact revert reason if applicable.
Call preflight_simulate or x402_preflight directly from any MCP-compatible agent framework. Your agent gets a structured APPROVED/REJECTED verdict with reputation flags — no HTTP wiring needed.
Agent config (claude_desktop_config.json)
{
"mcpServers": {
"arbisim-guard": {
"command": "node",
"args": [
"./gateway/dist/index.js",
"--mcp"
],
"env": {
"GATEWAY_API_KEY": "ask_free_••••"
}
}
}
}x402 payment safety check
// Check an x402 payment before it fires:
x402_preflight({
network: "avalanche-fuji",
from_address: "0x<agent>",
to_address: "0x<payee>",
token_address: "0x<USDC>",
amount_raw: "1000000" // 1 USDC
})
// Safety report:
{
"status": "REJECTED",
"flags": {
"low_agent_reputation": true, // score 12/100
"x402_payment_risk": true
},
"verdict": "ABORT — payee not trusted"
}Arbitrum-native agent framework by Ember. Supports GMX, Camelot, Aave, Pendle.
Multi-agent orchestration framework. Drop in the MCP plugin and call preflight_simulate from any agent.
Use the REST tool node or the MCP client adapter to integrate with your graph.
Every simulation returns a structured flag object. Each flag is an independent check that can abort execution.
Execution revert
Transaction would revert on-chain. Capital not spent.
High slippage
Price impact exceeds threshold. Swap unfavourable.
MEV sandwich
Surrounding txs detected. Front/back-run likely.
Unsafe allowance
Allowance exceeds transaction amount. Revoke risk.
Signature invalid
UserOp sigFailed from EntryPoint. AA20 violation.
Session key expired
validUntil in past. UserOp will be rejected.
Timeboost advised
Priority lane secures 200ms advantage. Premium shown.
Stylus ink limit
WASM execution exceeds ink budget. OOG likely.
Low ERC-8004 rep
Payee reputation score < 50 or unregistered. Payment risky.
x402 payment risk
ERC-20 transfer to low-reputation payee. Abort before paying.
Flat monthly pricing. One prevented bad transaction pays for the entire year.
Multi-chain. Native MCP tool. Works with Vibekit, Eliza, and LangGraph today.