TextKit

Send SMS from a LlamaIndex agent

Turn TextKit's MCP server into LlamaIndex tools with McpToolSpec and hand them to a FunctionAgent, so the agent can send texts and read delivery.

1. Get a test key

Create a test key on the API keys page of the console. It starts ssms_sk_test_, runs everything in the 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. Connect the MCP server

bash
pip install llama-index-tools-mcp llama-index-llms-openai
python
import asyncio
import os

from llama_index.core.agent.workflow import FunctionAgent
from llama_index.llms.openai import OpenAI
from llama_index.tools.mcp import BasicMCPClient, McpToolSpec


async def main():
    client = BasicMCPClient(
        "https://mcp.jointextkit.com",
        headers={"Authorization": f"Bearer {os.environ['TEXTKIT_API_KEY']}"},
    )
    spec = McpToolSpec(client=client, allowed_tools=["send_message", "get_message"])
    tools = await spec.to_tool_list_async()

    agent = FunctionAgent(
        tools=tools,
        llm=OpenAI(model="gpt-5-mini"),
        system_prompt="You send SMS with TextKit. Confirm the number and wording first.",
    )
    response = await agent.run('Text +15005550006 "Your order shipped."')
    print(response)


asyncio.run(main())

BasicMCPClient picks Streamable HTTP for an https URL that does not end in /sse, and passes headers on every request. allowed_tools keeps the agent to the two tools above; leave it out to load all of them. Any LlamaIndex LLM with function calling works in place of the one shown. 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 page.

3. 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 and register your use case 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 it needs.

Sources

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