marginal

sh.marginalPublished by marginal.shOfficial publisherv0.3.0Updated Oct 25, 2026

Email A/B tests for AI agents: subject lines, managed sends, open/click tracking, and results.

VerifiedStreamable HTTPWeb executableBusiness & Commerce

Overview

AI-generated overview

A remote MCP server for running email A/B tests from an AI assistant: subject lines, managed sends, open and click tracking, and results.

What you can do
Create and manage email A/B tests, including subject line variants, through the marginal service. Send emails through marginal's managed sending rather than your own mail infrastructure. Track opens and clicks on the messages it sends. Retrieve test results so the assistant can compare variants and report on performance.
When to use it
Useful when you want an assistant to set up, run and read out email subject-line A/B tests without wiring up separate sending and tracking tools. Suited to teams already using marginal for email testing.
Requirements
A remote endpoint at marginal.sh reached over streamable HTTP. A marginal account and API key from the marginal dashboard, supplied as a bearer token in the Authorization header. Network access to the service.
Before you install
The server requires your marginal API key as a bearer token in the Authorization header; treat it as a secret. It can send real email and create or change tests, so actions affect recipients and live campaigns. Open and click tracking data is collected by marginal, a third party. Sending may incur costs depending on your marginal plan.

Installation

In SourceWeft

  1. Open marginal in the dashboard and add it to a workspace.
  2. Connect Authorization token credentials. They are stored privately and never shown on public pages.
  3. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/sh.marginal%2Fmcp/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "marginal": {
      "type": "http",
      "url": "https://marginal.sh/mcp",
      "headers": {
        "Authorization": "Bearer <YOUR_TOKEN>"
      }
    }
  }
}

Tools

0
This server asks for a credential such as an API key, so SourceWeft could not read its tools without one and has not indexed them.

Version history

1
  1. v0.3.0LatestSep 16, 2026

Score

56% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts

    Publish an icon in the registry entry.

  • Documentation15 pts

    Declare a GitHub repository with a README, or serve resource_documentation in the OAuth protected-resource metadata.

  • LicenseNot applicable

    A hosted service is used under its provider's terms, so no license is expected here. This check is left out of the percentage.