Mastra

Connect a Mastra agent to Scalekit tools using MCP. Mastra has native MCP support via @mastra/mcp. Pass a Scalekit-generated URL and Mastra handles tool discovery automatically.

Why MCP for Mastra

Mastra’s tool system uses Zod schemas internally. The MCP path skips manual schema conversion. Mastra discovers tools and their schemas directly from the Scalekit MCP server.

Install

npm install @scalekit-sdk/node @mastra/core @mastra/mcp @ai-sdk/openai

Get a per-user MCP URL

Generate a Scalekit MCP URL for the user. This requires the Python SDK. Call this from your backend and pass the URL to your Mastra application:

# Backend (Python): generate once per user session
inst_response = actions.mcp.ensure_instance(
    config_name="your-mcp-config",
    user_identifier="user_123",
)
mcp_url = inst_response.instance.url
# Pass mcp_url to your Mastra app (e.g. via environment variable or API response)

See Configure an MCP server and Generate user MCP URLs to set up the config and generate the URL.

Build the agent

Pass the MCP URL to MCPClient. Mastra fetches the tool list and schemas automatically:

import { Agent } from '@mastra/core/agent';
import { MCPClient } from '@mastra/mcp';
import { openai } from '@ai-sdk/openai';

const mcpUrl = process.env.SCALEKIT_MCP_URL!; // set from your backend

const mcp = new MCPClient({
  servers: {
    scalekit: { url: new URL(mcpUrl) },
  },
});

const tools = await mcp.getTools();

const agent = new Agent({
  name: 'gmail_assistant',
  instructions: 'You are a helpful Gmail assistant.',
  model: openai('gpt-4o'),
  tools,
});

const result = await agent.generate('Fetch my last 5 unread emails and summarize them');
console.log(result.text);

await mcp.disconnect();