@sperax/tool-mev-shield

AI-powered MEV protection: sandwich attack detection, pre-swap risk analysis, mempool monitoring, and protection strategies

MEV Shield is an agent tool from SperaxOS, packaged headless so you can call it from any agent framework. It ships two things: the manifest — a JSON-Schema function definition a model can call — and the executor that runs the call against the real API.

There is no UI layer and no framework lock-in. It works anywhere TypeScript runs.

Install

npm install @sperax/tool-mev-shield

Usage

Call it directly

import { mevShieldExecutor } from '@sperax/tool-mev-shield';

const result = await mevShieldExecutor.invoke('analyzeTransaction', {"amount":"<amount>","chain":"<chain>"}, {
  messageId: 'msg-1',
});

console.log(result.content); // prose summary written for the model to read
console.log(result.state);   // typed data payload for your own UI

Give it to a model

import Anthropic from '@anthropic-ai/sdk';
import { MevShieldManifest, mevShieldExecutor } from '@sperax/tool-mev-shield';

const client = new Anthropic();

const response = await client.messages.create({
  model: 'claude-opus-4-8',
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Ask something this tool can answer' }],
  tools: MevShieldManifest.api.map((api) => ({
    name: api.name,
    description: api.description,
    input_schema: api.parameters,
  })),
});

for (const block of response.content) {
  if (block.type !== 'tool_use') continue;
  const result = await mevShieldExecutor.invoke(block.name, block.input, { messageId: response.id });
  console.log(result.content);
}

MevShieldManifest.api is already in JSON-Schema form, so it maps onto any tool-calling API — Anthropic, OpenAI, the Vercel AI SDK, or an MCP server — without translation.

Every executor returns a BuiltinToolResult — { success, content, state }. content is prose written for the model to read; state is the typed data payload for your own code. Executors never throw: a failed call comes back as { success: false, content: '<reason>' }, so a network blip degrades the answer instead of crashing the agent loop.

Configuration — required

This tool needs a backend you control. It will not work on a bare npm install alone.

The upstream API requires a secret key. That key is deliberately not bundled here — shipping it in an npm package would leak it to every consumer. Instead the executor calls a SperaxOS /webapi/* route, which holds the key server-side and injects it. That route is session-authenticated, so the public deployment at https://chat.sperax.io (the default origin) answers 401 to anonymous callers.

To use this tool you need one of:

• a SperaxOS deployment of your own, or
• any HTTP endpoint that implements the same request shape and supplies the key.

Point the package at it before importing the tool — the URL is resolved once, when the module first loads:

SPERAX_API_BASE_URL=https://my-speraxos.example.com

or in code:

import { configureSperaxApi } from '@sperax/agent-tools-core';

configureSperaxApi({ baseUrl: 'https://my-speraxos.example.com' });

// import the tool only after configuring, so the path resolves against your origin
const { mevShieldExecutor } = await import('@sperax/tool-mev-shield');

Inside a browser that already serves those routes at its own origin, requests stay same-origin and no configuration is needed.

If you want a tool that runs with zero setup, use one of the standalone tools — those call public APIs directly and need no key, no origin, and no backend.

Tool identifier

sperax-mev-shield

API reference

analyzeTransaction

Analyze a pending swap transaction for MEV vulnerabilities BEFORE submission. Returns risk score, attack vectors, estimated losses, and protection recommendations.

| Parameter | Type | Required | Description | | --- | --- | --- | --- | | amount | string | yes | Amount being swapped (human-readable, e.g. "1000"). | | chain | string | no | Chain name (default: ethereum). | | dex | string | no | DEX being used (e.g. "Uniswap", "Sushiswap"). | | slippageTolerance | number | no | Slippage tolerance in percent (e.g. 0.5). | | tokenIn | string | yes | Token being sold (e.g. "USDC"). | | tokenOut | string | yes | Token being bought (e.g. "ETH"). |

getMevExposure

Analyze historical MEV exposure for a wallet address. Shows total MEV losses, attack breakdown by type, and most-attacked tokens.

| Parameter | Type | Required | Description | | --- | --- | --- | --- | | address | string | yes | Ethereum wallet address to analyze. | | days | number | no | Number of days to look back (default: 30). |

getProtectionRecommendation

Get personalized MEV protection strategy recommendations based on transaction type, amount, chain, and urgency.

| Parameter | Type | Required | Description | | --- | --- | --- | --- | | amountUsd | number | yes | Transaction amount in USD. | | chain | string | no | Chain for the transaction. | | txType | string | yes | Type: "swap", "liquidity_add", "liquidity_remove", "bridge", or "other". | | urgency | string | no | Urgency: "low" (can wait), "medium" (within hours), "high" (ASAP). |

scanMempoolActivity

Scan current mempool conditions. Shows congestion, active MEV bots, gas conditions, recent MEV activity, and safety score for transacting now.

| Parameter | Type | Required | Description | | --- | --- | --- | --- | | chain | string | no | Chain to scan (default: ethereum). |

detectSandwichAttack

Forensically analyze a past transaction to detect if it was sandwich attacked. Identifies front-run/back-run transactions, bot addresses, and value extracted.

| Parameter | Type | Required | Description | | --- | --- | --- | --- | | chain | string | no | Chain (default: ethereum). | | txHash | string | yes | Transaction hash to investigate. |

Types

Shared types come from @sperax/agent-tools-core: BuiltinToolManifest, BuiltinToolResult, BuiltinToolContext, and the BaseExecutor class every tool executor extends.

Related

• @sperax/agent-tools-core — the tool contract
• All SperaxOS agent tools — tool-mev-shield is one of many
• SperaxOS — the agent workspace these tools were built for

License

Apache-2.0