marginal MCP MCP server

A hosted email marketing MCP server for AI agents that enables programmatic subject line A/B testing, managed email sends, open/click tracking, and performance analytics. It provides tools to generate variants, launch tests, retrieve results, and get recommendations, eliminating the need for separate ESP integrations like Mailchimp or Klaviyo.

Endpoint and access

OAuth sign-in: the first time you connect, your client opens the vendor's own authorization prompt in a browser.

OAuth sign-inEndpoint checked 2026-10-05Operated by marginal

MCP endpoint (Streamable HTTP)

https://marginal.sh/mcp

Vendor documentation

What you can do with it

Generate subject line variants from a campaign brief or seed text
Launch split tests to recipient lists with managed delivery
Track open and click metrics for email campaigns
Analyze experiment results to recommend next campaign angles

Connect from your client

Each snippet registers the same endpoint; pick the client you use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Claude Code

Run this once in a terminal. It registers a Streamable HTTP server. Use --scope project to write .mcp.json for the repo.

Claude Code configuration

claude mcp add --transport http marginal-mcp https://marginal.sh/mcp

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).

Codex configuration

codex mcp add marginal-mcp --url https://marginal.sh/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable marginal-mcp in your MCP settings.

Cursor configuration

{
  "mcpServers": {
    "marginal-mcp": {
      "url": "https://marginal.sh/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure). The type must be streamableHttp for a remote HTTP server.

Cline configuration

{
  "mcpServers": {
    "marginal-mcp": {
      "type": "streamableHttp",
      "url": "https://marginal.sh/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start marginal-mcp and inspect its tools.

VS Code configuration

{
  "servers": {
    "marginal-mcp": {
      "type": "http",
      "url": "https://marginal.sh/mcp"
    }
  }
}

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.

Gemini CLI configuration

gemini mcp add --transport http marginal-mcp https://marginal.sh/mcp

Claude Desktop

Merge this into claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\), then restart Claude Desktop.

Claude Desktop configuration

{
  "mcpServers": {
    "marginal-mcp": {
      "url": "https://marginal.sh/mcp"
    }
  }
}

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.

Windsurf configuration

{
  "mcpServers": {
    "marginal-mcp": {
      "serverUrl": "https://marginal.sh/mcp"
    }
  }
}

See all 347

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