Send iMessages from LangChain

What does an iMessage tool look like in LangChain?#

The same as any other tool: a function with a clear docstring, registered with your agent. The Blue Reacher API is plain HTTPS with a bearer key, so the whole wrapper is:

from langchain_core.tools import tool
import requests

@tool
def send_imessage(phone: str, message: str) -> dict:
    """Send an iMessage to a contact. Use for confirmed, human-approved outreach only."""
    r = requests.post(
        "https://api.bluereacher.com/v1/messages",
        headers={"Authorization": "Bearer brk_live_your_key"},
        json={"to": phone, "message": message},
    )
    return r.json()

• Bound to your model, "text the prospect the demo moved to 3pm" becomes an agent action on a dedicated line. Endpoint https://api.bluereacher.com/v1/messages, bearer auth; onboarding covers scheduled sends.

How do inbound replies reach the agent?#

Webhooks carry the inbound side: Blue Reacher posts every reply, delivery state, and opt-out to endpoints you host, and a FastAPI route invokes your graph. The webhook resumes a LangGraph thread; phone maps to thread ID.

• Delivery states matter more than they look. An agent knowing a message was delivered but unanswered for two days can follow up; one seeing an RCS or SMS fallback can shorten its message the way you would on plain SMS.
• STOP handling costs you nothing: it's detected and the contact suppressed platform-side, before your code enforces it.

Should I use the MCP server instead of raw tools?#

If your agent stack loads MCP servers already, yes, it's less code you own: Blue Reacher ships an MCP server exposing messaging as typed tools, and LangChain's MCP adapters load them like any other toolset.

• The raw-API route wins when you want tight control over the tool surface, custom docstrings that steer the model, or guardrail wrappers.
• On guardrails: an agent with a send_message tool is production outbound, not a demo. The patterns that hold up:

• Human-in-the-loop on first contact: agent drafts, a human approves, the tool sends; autonomy comes later, on replies
• Allowlist the recipients: the tool checks the contact exists in your CRM segment before sending, so a hallucinated number is a no-op
• Let the platform own compliance: STOP suppression and availability checks happen in Blue Reacher, not in your prompt
• Log tool calls against delivery states, so you can audit what the agent sent and what actually landed

What does this cost to run?#

Pricing for agent workloads: $249 per line per month with unlimited iMessages (50 opted-in / 30 cold new contacts a day) and no per-message metering, so an agent handling hundreds of conversations runs no variable bill.

• $199 per line at 4+ lines, or $1,949 per line per year (about $162.50 a month) with the $449 activation waived on annual.
• No A2P registration required, so no carrier approval sits between prototype and production. White-glove onboarding includes API and webhook setup, and reviewing your tool schema.