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# `x402/mcp.mpp` \[Add MPP to an x402 MCP tool]

Wraps an official x402 MCP tool handler so calls can pay through MPP or x402 metadata.

## Usage

```ts [server.ts]
import { x402ResourceServer } from '@x402/core/server'
import { mpp } from 'mppx/x402/mcp'

const paid = mpp(resourceServer, {
  accepts,
  resource: {
    description: 'Premium search',
    url: 'mcp://tool/search',
  },
  secretKey: process.env.MPP_SECRET_KEY!,
})

const search = paid(async ({ query }: { query: string }) => ({
  content: [{ text: `result:${query}`, type: 'text' }],
}))
```

The resource URL must use the canonical `mcp://tool/{toolName}` shape without another path segment, query, or fragment. An unpaid call returns one MCP payment error containing both MPP Challenges and the x402 payment requirements.

x402 Credentials and lifecycle hooks stay with `@x402/mcp`. MPP source-chain EVM Credentials reuse the x402 resource server for verification and settlement; x402-only hooks run only for x402 calls.

## Return type

```ts
type ReturnType = <arguments_ extends Record<string, unknown>>(
  handler: PaymentWrappedHandler<arguments_>,
) => MCPToolCallback<arguments_>
```

## Parameters

### config

* **Type:** `Config`

Existing x402 MCP payment settings plus the MPP realm and secret. `resource.url` must match the canonical tool URL described above; `resource.description` and `resource.mimeType` remain optional. `secretKey` must contain at least 32 bytes.

### resourceServer

* **Type:** `x402ResourceServer`

Existing x402 resource server used for requirement metadata, verification, and settlement.