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Overview

OneCLI connects AI agents to Resend using an API key. Agents can send transactional emails, check delivery status, and manage contacts. The gateway injects the API key into requests to the Resend API automatically. This is useful for agents that need to send notifications, alerts, or reports by email without configuring SMTP.

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What you will set up

  • A Resend API key with sending or full access
  • Automatic key injection on Resend API requests
  • Per-agent, per-tool access, such as rate limits on sends

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Setup

1

Create an API key in Resend

Go to resend.com/api-keys and create a new API key. Choose the appropriate permission level (sending access or full access). Copy the key.
2

Connect in OneCLI

Open the OneCLI dashboard, go to Connections > Resend, and paste your API key.
OneCLI connect window for Resend, showing the setup guide link and the fields to fill in.

The Resend connect window in OneCLI.

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What agents can do

  • Send emails with specified from address, recipients, subject, and HTML or plain text body
  • Send emails with attachments
  • Check the delivery status of a sent email (delivered, bounced, complained)
  • List sent emails and their statuses
  • Manage contacts and audiences (create, list, update, delete contacts)
  • Send batch emails to multiple recipients
  • Use verified domains for sending

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Controlling access

Access is per agent: grant the connection to each agent that needs it, choosing per tool what runs freely, what needs human approval, and what stays blocked — a read-only agent is a single grant. Organization rules add guardrails on top, like rate limits and blanket blocks. Everything is checked before credential injection, so a blocked request never reaches Resend.

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FAQ

Create a new key at resend.com/api-keys, then paste it into Connections > Resend. Agents pick it up automatically. Then delete the old key.
Don’t set RESEND_API_KEY in the agent’s environment. Store it in OneCLI, and the gateway injects it at the proxy. See How it works.
Yes. Add a rate limit with rules, or put sending behind approval when you grant the connection.