Set up Knock Knock

Create your account.

Knock Knock is free. Each person can send up to 30 messages per calendar month (UTC). First messages and replies count; received messages and drafts do not. At the limit, sending pauses until next month, while reading and drafting remain available. No payment details are required.

Create account Sign in

Add someone you work with.

Open Get started and create a private invite link. The other person opens it, signs in, and chooses their own @username. Check Contacts and accept any request that is waiting.

Connect Claude.

In Claude, open Customize > Connectors. Choose + > Add custom connector, paste the address below, and finish signing in to Knock Knock. On Team and Enterprise plans, an owner adds the connector before members connect it.

https://get-knockknock.com/mcp/inbox

Claude's current connector guide

Connect ChatGPT.

In ChatGPT, open Settings > Security and login and turn on Developer mode. Open Plugins, choose the plus button, and add the same server address. Review the tools, complete the Knock Knock sign-in, and select the contact you want this connection to read.

https://get-knockknock.com/mcp/inbox

Developer mode availability depends on your account and workspace policy. ChatGPT's current connection guide

Connect Claude Code, Codex, or Cursor.

Coding agents connect with one command and sign in the same way: a browser window opens, you sign in to Knock Knock and choose which contacts that agent can read. Nothing is granted by the command itself.

Claude Code

claude mcp add --transport http knock-knock https://get-knockknock.com/mcp/inbox

Then type /mcp inside Claude Code and choose Knock Knock to sign in, or run claude mcp login knock-knock. Claude Code's current MCP guide

Codex

codex mcp add knock-knock --url https://get-knockknock.com/mcp/inboxcodex mcp login knock-knock

Codex's current MCP guide

Cursor

Add to Cursor

Or add this to your mcp.json and complete the sign-in Cursor opens:

{
  "mcpServers": {
    "knock-knock": {
      "url": "https://get-knockknock.com/mcp/inbox"
    }
  }
}

Cursor's current MCP guide

Any agent can read the same setup and workflow as plain text at https://get-knockknock.com/skill.md. Reading it does not connect or authorize anything.

Add the optional Claude skill.

The connector includes the Knock Knock inbox and drafting instructions when your AI connects. Claude can also install the same guide as a skill so the workflow is available whenever it is relevant. Downloading the skill does not install it or connect your account.

Download for Claude Download SKILL.md

In Claude, upload the ZIP from Customize > Skills > + > Create skill > Upload a skill. Skills require the related Claude capability to be enabled. ChatGPT receives the connector's usage instructions, but adding the MCP server does not install this downloaded file as a native ChatGPT skill.

Claude's current skill guide

Try the first message.

Enable Knock Knock in the AI conversation, then use this prompt:

Check my Knock Knock inbox. Tell me what needs my attention, then draft a reply only if I ask.

The AI can read only the approved contacts selected for that connection.
It can open a supported attachment only when you ask for its contents.
It can prepare a reply draft. Drafting a first message to a contact is optional: you choose it when you connect, or later in Knock Knock's AI settings.
A draft is not sent. Open Knock Knock, check the recipient and exact words, then choose Send in the browser.

Open inbox Check AI access