The agent provisions itself
Through MCP it opens a sandbox, gets test numbers and sends its first message, with nobody clicking in a dashboard. A person approves once, when a real sender identity and a budget are attached.
Agent Lab Communication SDK
One agent.
Every channel.
A messaging API built for AI agents. One MCP server and one SDK for the LINE, WhatsApp, Messenger, Instagram, SMS and email your customers use, and the Slack, Teams and LINE WORKS your colleagues use. The agent provisions itself and pays per delivered message; each channel's rules, like the 24-hour window, template approval and opt-out, are handled by the platform.
Communication SDK
MCPSDKOne layer for sending, waiting for replies, rules and billing, across every channel.
LINE
WhatsApp
Messenger
Instagram
SMS
Email
Slack
Teams
LINE WORKSAny agent. Any channel.
LINE, WhatsApp and SMS for customers, Slack, Teams and LINE WORKS for colleagues, all through the same messages_send.
- LINE
- WhatsApp
- Messenger
- Instagram
- SMS
- Email
- Slack
- Teams
- LINE WORKS
Channel architecture
One agent architecture, native to every channel.
The agent only needs a few tools: contacts_resolve, messages_send, messages_wait. Each channel's format, rules, billing and inbound events are translated in the layer between; a button is a button on LINE and a link on SMS.
Crescendo Lab has run LINE, Messenger, SMS and email at scale for years in MAAC, CAAC and its self-serve products. Slack and Teams are already Agent Lab entry points. The Communication SDK wraps them all in a layer agents can use directly.
> Tell Ms. Wang her order shipped on LINE; SMS her if unread in 6h
contacts_resolveMs. Wang → LINE friend ✓ · phone verified ✓
messages_sendline · shipping template · delivered
messages_waitnot read within 6h
messages_sendsms · same message, fit to 160 chars · delivered
LINE went unread, so I sent an SMS. Delivered. Cost: US$0.04.
Built for agents
Messaging APIs were made for engineers reading docs. This one is made for agents.
Agents don't fill in forms, wait for approval emails or remember every channel's rules. The platform does.
Channel rules, enforced for you
The 24-hour window, template approval, opt-out and quiet hours are checked before sending. A refused send says why and what to do next, so the agent never guesses.
Waiting for a reply is a tool
One customer across channels is one conversation. messages_wait lets the agent wait for a reply or a read, or move to the next channel when time runs out.
A budget with a ceiling
Each agent has a daily and monthly spend cap and stops at it, so a loop can't burn a month of SMS. Every message is logged and exportable.
From sandbox to live
Connect → Sandbox → First message → Live
The agent does the first three steps itself; going live needs a person.
Connect
One command adds the MCP server to Claude Code, Codex or your own agent.
Sandbox
The agent opens a sandbox with a test LINE account and SMS number, free.
First message
Send to your own phone and watch it switch between LINE and SMS.
Live
A person connects the LINE Official Account, WhatsApp number or SMS sender name and sets the budget.
FAQ
Before you start
What is the Communication SDK?
Crescendo Agent Lab's messaging API whose users are AI agents: through one MCP server or SDK, an agent messages customers on LINE, WhatsApp, Messenger, Instagram, SMS and email, or colleagues on Slack, Microsoft Teams and LINE WORKS, and waits for replies; each channel's rules and billing are handled by the platform.
How do I start?
Request access with the form below. Once we confirm the use case we open your workspace and sandbox, and your agent connects to the MCP server and sends its first message.
Other messaging platforms have MCP servers. What's different?
Most messaging platforms' MCP servers help a coding agent look up API docs, or let an agent operate an account a person has signed in to. The Communication SDK makes the agent itself the user: it provisions a sandbox, sends within each channel's rules, waits for replies and switches channels within a budget. And LINE is a first-class channel, not an add-on.
How is it priced?
Per delivered message, like other messaging platforms; LINE and WhatsApp channel fees pass through at the official rates. Slack, Teams and LINE WORKS carry no channel fee. For a volume quote, use the form or email us.
Can my agent request access for me?
Yes. Have it read https://agentlab.cresclab.com/channels.md, which explains how. It should ask you before sending your name and email.
Request access.
Start in the sandbox.
- Tell us which channels your agent needs
- Tell us your monthly volume and we'll quote
- The sandbox and test credit are ready once your workspace is open
Want your agent to read it first? channels.md
Got it
We will email you to open your workspace and sandbox.