---
name: arbitrum-mpp-transaction-preflight-production.up.railway.app
description: This host exposes a single endpoint that simulates Ethereum-compatible transactions on Arbitrum One (chainId 42161) before they are broadcast. It returns gas estimates, simulation success/failure, return data, target classification (contract vs EOA), and risk signals — all without spending gas or altering chain state.
host: arbitrum-mpp-transaction-preflight-production.up.railway.app
---

# arbitrum-mpp-transaction-preflight-production.up.railway.app

arbitrum-mpp-transaction-preflight-production.up.railway.app is a narrow, single-purpose preflight service for Arbitrum One. It serves agents and developers who need to dry-run transactions to catch failures, estimate costs, and assess risk before committing to on-chain execution. It does not execute transactions and does not support any chain other than Arbitrum One.

## When to use this host

Use this host when an agent needs to validate a transaction on Arbitrum One before broadcasting — specifically to check gas cost, detect likely revert conditions, classify the target address, or assess risk without spending gas. Do not use it for transactions on Ethereum mainnet, Optimism, Base, Polygon, or any other EVM chain; chain-specific preflight services or general-purpose simulation tools (e.g., Tenderly, Alchemy Simulation API) would be needed for those networks. Do not treat simulation success as a guarantee of on-chain success — final state may differ due to block-level changes between simulation and submission. This host is not a transaction broadcaster and cannot submit transactions to the network.

## Capabilities

### Transaction Simulation

Simulates a transaction on Arbitrum One and returns chain metadata, gas estimates, simulation outcome, target type classification, and risk signals — enabling safe pre-submission validation.

- **`preflight-arbitrum-transaction`** — Simulates an Ethereum transaction on Arbitrum One before submission, returning chain details, gas estimates, simulation success/return data, target type, and risk signals.

## Skill reference

### `preflight-arbitrum-transaction`

**Arbitrum Transaction Preflight** — Simulates an Ethereum transaction on Arbitrum One before submission, returning chain details, gas estimates, simulation success/return data, target type, and risk signals.

*Use when:* Use when an agent needs to validate or dry-run a transaction on Arbitrum One before broadcasting it — to check gas cost, confirm simulation success, detect contract vs EOA targets, and assess risk level without spending gas.

*Not for:* Do not use for transactions on other chains (mainnet, Optimism, Base, etc.); this endpoint is specific to Arbitrum One (chainId 42161). Not a substitute for on-chain execution — simulation results are not guaranteed to match final state.

**Inputs:**

- `to` (string, required) — Destination address of the transaction (checksummed hex).
- `from` (string, required) — Sender address of the transaction (checksummed hex).
- `data` (string, required) — ABI-encoded calldata for the transaction. Use '0x' for plain ETH transfers.
- `valueEth` (string, required) — ETH value to send with the transaction, expressed as a decimal string in ETH (not wei).

**Returns:** Returns Arbitrum One chain details, echoed transaction fields, target type (EOA/contract), simulation success with returnData, gas estimate and cost in ETH, a risk score/level/warnings object, and the block/timestamp of the check.

**Example:** `{"to": "0x0000000000000000000000000000000000000002", "from": "0x7e571E959cC7C75Ccdd2eAC24f8775ea2eAa2F09", "data": "0x", "valueEth": "0"}`

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