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Claude Agent SDK + iMessage — Build AI Agents That Text

Give your Claude-powered AI agents the ability to send and receive real iMessages. Connect Sendblue via a custom REST API tool or the MCP server to build agents that communicate through the most engaging messaging channel.

How to Connect Claude Agent SDK + Sendblue

1

Get Sendblue API Credentials

Create a Sendblue account at dashboard.sendblue.com. Copy your API key and secret — these authenticate every message your agent sends.

2

Define the Messaging Tool

Option A: Define a custom tool that POSTs to https://api.sendblue.co/api/send-message with phone number and content. Option B: Attach the sendblue-mcp server as an MCP tool provider.

3

Configure Webhooks for Replies

Set up a Sendblue webhook to receive incoming messages. Route replies to your agent so it can process responses and continue the conversation autonomously.

4

Deploy Your Agent

Run your agent in production. It can now send iMessages as part of its reasoning loop — notifying users, confirming actions, or having full conversations over text.

Key Capabilities

Autonomous Outreach

Your agent decides when to text. Appointment reminders, order confirmations, follow-ups — the agent determines the right moment and sends the message without human intervention.

Conversational Agents

Build agents that hold real text conversations. The agent sends a message, receives a reply via webhook, processes it with Claude, and responds — creating a natural back-and-forth over iMessage.

Two Connection Methods

Use Sendblue's REST API as a custom tool for maximum control, or connect the MCP server for a faster setup with pre-built tools. Both approaches work with the Claude Agent SDK.

Media Messaging

Agents can send images, PDFs, and contact cards alongside text messages. Share receipts, product photos, or vCards — all through the same API call.

Delivery Intelligence

Check whether messages were delivered or read. Your agent can adapt its behavior based on delivery status — retry on failure, follow up after read, or escalate when undelivered.

iMessage + SMS Fallback

Sendblue detects iMessage support automatically. iPhone users get blue bubbles; Android users get SMS. Your agent reaches everyone without conditional logic.

Why AI Agents Need iMessage

The Claude Agent SDK lets you build AI agents that take real-world actions — searching databases, calling APIs, writing code. With Sendblue, you add one of the most powerful actions an agent can take: texting a human.

iMessage is uniquely effective for agent-to-human communication. It delivers with blue bubbles on iPhone (70%+ of US smartphone users), supports read receipts so your agent knows when messages are seen, and achieves 30-45% response rates — far higher than email or push notifications.

Consider the use cases: a customer support agent that texts order updates and handles return requests over iMessage. A scheduling agent that confirms appointments and sends reminders. A sales agent that follows up with prospects and books meetings. Each of these requires the agent to communicate reliably with humans, and iMessage is the highest-engagement channel available.

The connection is straightforward. Define a tool that calls https://api.sendblue.co/api/send-message with a phone number and message body, or attach the Sendblue MCP server for pre-built send, receive, and status tools. Your agent gets messaging capabilities in minutes, and you can pair it with Sendblue's native CRM integrations (HubSpot, Salesforce, GoHighLevel) for end-to-end customer workflows.

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Frequently Asked Questions

How do I give a Claude agent the ability to send iMessages?

Define a custom tool in your Claude Agent SDK configuration that calls Sendblue's REST API at https://api.sendblue.co/api/send-message. Alternatively, connect the Sendblue MCP server (sendblue-mcp) as a tool provider. Both approaches let your agent send iMessages as part of its action loop.

Can a Claude agent receive and respond to iMessages?

Yes. Configure a webhook on Sendblue to receive incoming messages, then pass those messages to your agent as context. The agent can process the reply and send a response back through Sendblue's API, creating a fully autonomous conversational loop.

What is the difference between the REST API tool and the MCP server approach?

The REST API approach gives you full control — you define a custom tool that makes HTTP requests to Sendblue's endpoints. The MCP server approach is faster to set up — you connect the sendblue-mcp server and get pre-built tools for sending, receiving, and checking message status. Both work with the Claude Agent SDK.

Is this a native Anthropic or Sendblue integration?

No. There is no built-in Sendblue plugin for the Claude Agent SDK. You connect them by defining Sendblue's API as a custom tool or by attaching the Sendblue MCP server. This is a standard pattern for extending Claude agents with external capabilities.