Resend
Send transactional email and manage domains, audiences, contacts and broadcasts via Resend.
About
Resend ships in the w6w first-party pack. It declares 24 actions, 2 health checks, and the host runs its code in a sandbox that never sees the credential.
- App id
io.w6w.resend- Version
- 0.1.1
- Author
- w6w
- Licence
- MIT
- Categories
- Email · Communication
Overview
Resend is a transactional and marketing email platform, and this app sends and manages email through it: send a single transactional email or up to a hundred in one batch, and create and manage the domains, audiences, contacts and broadcasts a sending program depends on.
Both send actions support idempotency, so a retried workflow step can’t accidentally send the same email twice — the key defaults to the step’s own invocation id, stable across a retry and different for the next send. Domain actions cover adding a new sending domain, reading back the DNS records it needs, and asking Resend to re-verify it once those records are in place. Audience and contact actions manage subscriber lists and their subscription state, and broadcast actions draft, list and send a campaign to a chosen segment.
This app covers sending and the audience infrastructure around it; API key creation, inbound email, and Resend’s templates and automation features are left out, since minting a live credential or handling raw message bodies belongs to a different kind of surface than a workflow action.
Build with Resend
Three routes to the same 24 actions. The Workflow tab is generated from Resend's own manifest and carries its real ids, so it is copy-pasteable; the Code and CLI examples are the same call for any action on any app, so every app-specific value in them is a blank you fill in.
Create a broadcast
broadcast-create Draft a broadcast to a segment. It is not sent until you send or schedule it.
Verify a domain
domain-verify Ask Resend to re-check a domain's DNS records. Read the result with Get a domain.
A workflow step names the app and the action, and the editor fills in the
connection when you pick one. This is the Step shape from the
workflow spec, carrying Resend's real ids.
{
"manifestVersion": "2",
"name": "resend-example",
"steps": [
{
"id": "audience-create",
"uses": {
"app": "io.w6w.resend",
"action": "audience-create",
"connection": "conn_YOUR_CONNECTION_ID"
},
"with": {
"name": "<name>"
}
}
]
}Here are some of the things you can do
-
Create an audience
performaudience-create -
List API keys
readapi-key-list -
Get an audience
readaudience-get -
List audiences
readaudience-list -
Create a broadcast
performbroadcast-create
+19 more actions available
Every app-specific value here is a blank you have to fill in. An
app action is reached through the connection that authenticates it, so the
address is a connection id, not the app id — and connections belong to your account,
so a public page cannot know yours. Create one for Resend, then fill in
the three blanks: conn_YOUR_CONNECTION_ID, the action key, and the
parameters that action declares. The call itself is real — the shape is transcribed
from the studio's own snippet builder, which prints the same kind of blanks — but
nothing in it is specific to Resend. The Workflow tab is where this app's
real ids are.
npm install @w6w/sdkyarn add @w6w/sdkpnpm add @w6w/sdkdeno add npm:@w6w/sdkimport { W6wClient, isActionRun } from "@w6w/sdk";
// Reads W6W_BASE_URL and W6W_TOKEN from the environment when omitted.
const client = new W6wClient();
const envelope = await client.run({
urn: "conn_YOUR_CONNECTION_ID",
action: "audience-create",
payload: {
name: "<value>",
},
});
if (isActionRun(envelope)) console.log(envelope.value);npm install -g @w6w/cliw6w run conn_YOUR_CONNECTION_ID --action audience-create --payload '{"name":"<value>"}'Give an AI agent Resend — without giving it Resend's credentials. One MCP endpoint exposes every app, function and workflow the caller is entitled to, as tools it can discover and run. Access is granted per team while we onboard.
One tool call{
"name": "w6w_invoke",
"arguments": {
"ref": "app:io.w6w.resend#audience-create",
"input": {
"name": "<name>"
}
}
}
Every tool names its target with a single ref. The
app: form above doesn't name a connection at all — the
host resolves which of the caller's Resend connections to sign
with, and refuses rather than guesses when the answer is ambiguous.
What the agent gets
Credentials it can't read
The token is attached host-side, at the moment of the call. It is never a tool argument, never in the model's context, and never in a transcript — so a prompt injection has nothing to exfiltrate.
A tool surface scoped to the caller
Tools are derived per end user from what that person has actually connected and is entitled to — not one shared bot identity carrying the union of everyone's access.
A durable workflow in one call
Multi-step work runs on the workflow engine and returns a run handle the agent can poll — retries, branching and state survive the conversation that started them.
Health-aware discovery
Resend's declared health checks are on the surface too, so an agent can tell "the vendor is down" from "your credential expired" before it burns a retry on either.
The MCP surface is part of the hosted platform. Resend itself is MIT, and the runtime that executes it is source-available (FSL).
Health checks
Resend declares its own checks, so its health is a property of the app rather than something the host guesses at.
Resend platform status
No machine-readable status API, Atom or RSS feed is published — status.resend.com is a client-rendered page that answers 200 with the same HTML on every path.