# Send SMS from a Mastra agent

Source: https://jointextkit.com/integrations/mastra
Index: https://jointextkit.com/llms.txt

Register TextKit as an MCP server in Mastra and give its tools to an agent,
so the agent can send texts, check delivery and work with contacts.

## 1. Get a test key

Create a test key on the [API keys](/console) page of the console. It starts
`ssms_sk_test_`, runs everything in the [sandbox](/docs/sandbox), and texts no
real phone except your own verified one. Put it in your environment as
`TEXTKIT_API_KEY`:

```bash
export TEXTKIT_API_KEY=ssms_sk_test_...
```

## 2. Add the MCP client

```bash
npm install @mastra/mcp@latest
```

Create the client in your Mastra project, for example `mcp/textkit.ts`. The
key goes in `requestInit.headers` and stays in the environment, out of your
source:

```typescript
import { MCPClient } from '@mastra/mcp';

export const textkit = new MCPClient({
  id: 'textkit',
  servers: {
    textkit: {
      url: new URL('https://mcp.jointextkit.com'),
      requestInit: {
        headers: { Authorization: `Bearer ${process.env.TEXTKIT_API_KEY}` },
      },
    },
  },
});
```

## 3. Give the tools to an agent

```typescript
import { Agent } from '@mastra/core/agent';
import { textkit } from '../mcp/textkit';

export const notifier = new Agent({
  id: 'notifier',
  name: 'Notifier',
  instructions: `
    You send SMS with the TextKit tools.
    Confirm the number and the wording before you send.
  `,
  model: 'openai/gpt-6.1-sol',
  tools: await textkit.listTools(),
});
```

Use any model string Mastra supports. Run it from a workflow, a route or a
script:

```typescript
const response = await notifier.generate('Text +15005550006 "Your order shipped."');
console.log(response.text);
```

When each of your users brings their own TextKit key, build the client per
request and pass `await client.listToolsets()` as `toolsets` to
`generate()` instead of fixing `tools` on the agent, then call
`disconnect()`. The server exposes 142 tools: messages, verification, numbers, contacts,
segments, broadcasts, automations and account reads. Each one is a single API
call with your key, so the key's scopes, rate limits and send checks apply
unchanged. The full list is on the [MCP server](/docs/mcp) page.

## 4. Check the sandbox run

`+15005550006` is a sandbox number that always ends `delivered`, so the
agent's tool call returns a message with an id starting `msg_` and nothing
reaches a phone. The message also shows in the console's message log, tagged
`Test`. Ask for a text to your own number instead and, once that number is
verified under Settings, it really arrives (up to 10 a day, ending
"- via TextKit sandbox").

## Go live

Swap the test key for a live one (`ssms_sk_live_`). A live text needs a
number on your account: [buy one](/docs/numbers) and
[register your use case](/docs/compliance) with the carriers. When the
account has one number, `from` is optional and the text goes out from it.
To limit what an agent can do with a live key, give it one with only the
[scopes](/docs/authentication) it needs.

## Sources

- [Mastra: MCP overview](https://mastra.ai/docs/mcp/overview)