GOAT SDK Plugin

What is the GOAT SDK plugin?

The @mandate.md/goat-plugin package wraps Mandate’s policy engine as a GOAT SDK plugin. It exposes two tools: mandate_transfer for ERC20 transfers and mandate_x402_pay for x402 payment flows. Every tool call validates against your Mandate spending policies before signing or broadcasting. The plugin extends PluginBase<EVMWalletClient> and works with any EVM chain supported by GOAT.

Installation

bun add @mandate.md/goat-plugin @goat-sdk/core

@goat-sdk/core is a peer dependency (>=0.3.0). Install it alongside the plugin.

Usage

import { mandate } from '@mandate.md/goat-plugin';
import { createWalletClient, http } from 'viem';
import { privateKeyToAccount } from 'viem/accounts';
import { baseSepolia } from 'viem/chains';

const walletClient = createWalletClient({
  account: privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`),
  chain: baseSepolia,
  transport: http(),
});

const mandatePlugin = mandate({
  runtimeKey: process.env.MANDATE_RUNTIME_KEY!,
  privateKey: process.env.PRIVATE_KEY! as `0x${string}`,
  chainId: 84532,
  rpcUrl: 'https://sepolia.base.org',
});

Pass the plugin to your GOAT agent’s plugin list. The agent can now call mandate_transfer and mandate_x402_pay as tools.

Tools

Tool	Description
`mandate_transfer`	Transfer ERC20 tokens with policy enforcement. Accepts `to`, `amount`, `tokenAddress`, and optional `waitForConfirmation`.
`mandate_x402_pay`	Pay for an x402-gated resource. Accepts `url` and optional `headers`.

Both tools create a MandateWallet internally, validate the transaction against the Mandate API, sign locally, and broadcast. Your private key never leaves the process.

Configuration

Parameter	Type	Required	Description
`runtimeKey`	`string`	Yes	Mandate runtime key (`mndt_live_...` or `mndt_test_...`)
`privateKey`	`0x${string}`	Yes	Agent wallet private key (hex, with `0x` prefix)
`chainId`	`number`	No	EVM chain ID. Defaults to `84532` (Base Sepolia).
`rpcUrl`	`string`	No	RPC endpoint URL. Defaults to the chain’s public RPC.

Error handling

The plugin throws plain Error objects with descriptive messages. This matches GOAT SDK conventions where tool errors surface as strings to the LLM.

// Policy block:
// "Transfer blocked by Mandate policy: daily_limit_exceeded"

// Approval required:
// "Transfer requires approval. IntentId: int_abc123"

If your agent needs structured error handling, use the @mandate.md/sdk directly. The SDK throws typed errors: PolicyBlockedError, ApprovalRequiredError, and CircuitBreakerError.

Store runtimeKey and privateKey in environment variables. Never hardcode credentials in source files.

Next Steps

Integrations Overview

Compare all supported agent frameworks and choose the right one.

MandateWallet

Use MandateWallet directly for full control over the validate-sign-broadcast flow.

Handle Errors

Learn how to catch and respond to every Mandate error type.

​What is the GOAT SDK plugin?

​Installation

​Usage

​Tools

​Configuration

​Error handling

​Next Steps

Integrations Overview

MandateWallet

Handle Errors

What is the GOAT SDK plugin?

Installation

Usage

Tools

Configuration

Error handling

Next Steps