dummy-mcp

A toy MCP server with two mocked PostHog-style tools (get_trends, get_funnel) for experimenting with the MCP Streamable HTTP transport and the @posthog/mcp analytics SDK.

Setup

npm install

Config lives in .env. Copy the template and fill in your key:

cp .env.example .env

Then set in .env:

• POSTHOG_API_KEY — your project API key (the phc_… value from PostHog → Project Settings → Project API Key). Personal API keys (phx_…) are rejected with 401 personal_api_key.
• POSTHOG_HOST — optional. Defaults to the local dev stack (http://localhost:8010); uncomment it and use https://us.i.posthog.com (or https://eu.i.posthog.com) for cloud.

Run

node index.js

You should see:

server.ready http://localhost:3000/mcp

Override the port with PORT=4000 node index.js if needed.

All tool-call logs (get_trends …, etc.) go to stderr in this terminal. Leave it running.

Connect from Claude Desktop

Claude Desktop speaks stdio MCP, so we bridge to the HTTP server with the mcp-remote proxy.

Edit ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "dummy-mcp": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "http://localhost:3000/mcp", "--transport", "http-only"]
    }
  }
}

Then restart Claude Desktop. Ask it to invoke get_trends or get_funnel and watch the live logs in the terminal running node index.js.

Tools

• get_trends(event, days=7) — mocked daily time series
• get_funnel(steps[], days=7) — mocked funnel breakdown with conversion rates