Connect Penlog to ChatGPT

ChatGPT connects to Penlog through Developer mode, which lets you register any remote MCP server. You paste one URL, ChatGPT discovers our server and registers itself, and you approve the connection by signing in with Apple.

Penlog MCP server URL

https://mcp.penlog.app

That is the whole credential. There is no token, client ID, or secret to paste — Penlog registers your client automatically and then asks you to sign in.

Before you start

  • Penlog Pro is required. Without it the connection succeeds and every tool call returns a 402.
  • Developer mode works on a Free ChatGPT account. This is worth saying plainly because a lot of third-party write-ups claim it needs Plus or Pro. We connected Penlog on a Free account to check.
  • It is a web app feature. Set the connection up at chatgpt.com, not in the mobile app.
  • A directory listing is not required, and not involved. You are pointing ChatGPT at our server directly.

Add the connector

  1. Open Settings → Plugins in ChatGPT on the web, and turn on Developer mode if it is not already on. OpenAI renamed these menus in July 2026 — on an older build the same screens are called Connectors, with Developer mode under Advanced.
  2. Choose + Create app.
  3. Paste https://mcp.penlog.app as the MCP server URL.
  4. Choose OAuth for authentication. ChatGPT reads our server's metadata and selects Dynamic Client Registration on its own; the read, seed, and write scopes are discovered and pre-checked. Leave them as they are unless you want a read-only connection.
  5. Create the app. ChatGPT shows a Sign in with Penlog card.
  6. Sign in with Apple, review the scopes on our consent screen, and choose Allow. ChatGPT confirms with "Penlog is installed."

There is no place for an API token

ChatGPT's New Plugin dialog offers OAuth, No Auth, or Mixed. It has no API-key or custom-header field, so a plg_live_ bearer token minted in the Penlog app cannot be used to connect ChatGPT — there is nowhere to put it. OAuth is the only path here. Tokens remain useful for CLI tools and self-hosted agents; see Remote MCP clients.

Check that it worked

Ask for something only your journal can answer:

What are my open tasks in Penlog?

A good negative test is asking about a date you know you never wrote on. A working connection says it has no page for that date. An answer that invents content means ChatGPT is not actually calling the connector.

Deep research and search

Alongside the six core tools, Penlog exposes search and fetch aliases that return OpenAI's deep-research shape ({id, title, text, url, metadata}), so your handwriting is citable in deep-research runs. They are the same underlying data as search_pages and get_page.

If it doesn't connect

What you seeWhat it means
No + Create app option Developer mode is off, or you are in the mobile app rather than the web app.
Registration fails before any sign-in The URL has a path or a typo. It is exactly https://mcp.penlog.app.
Every tool returns 402 The Penlog account you signed in as is not Pro.
One tool returns 403 You unchecked a scope during setup. Reconnect and approve it.

More cases are in Troubleshooting.

Disconnecting

Delete the plugin in ChatGPT, or revoke it from Penlog under Settings → Connected Apps. Revocation is immediate.