Connect Fine Structure to ChatGPT

ChatGPT can talk to any remote MCP server, but the door is behind developer mode rather than the ordinary apps list. Once the switch is on you create a connector, paste the Fine Structure endpoint, and ChatGPT discovers the tools. Expect a confirmation prompt whenever it wants to change something.

Before you start

• A Fine Structure account on the free tier or above.
• A ChatGPT account on the web. OpenAI's developer mode guide lists Pro, Plus, Business, Enterprise and Education accounts as eligible.
• OpenAI notes that developer mode availability can depend on account and workspace policy, so on a managed workspace an administrator may need to allow connector creation before you see it.
• A desktop browser. This is a web settings flow, not a mobile one.

Step by step

1. Open ChatGPT Settings.
2. Go to Security and login and turn on Developer mode. That is the location given in OpenAI's developer mode guide, which is the page to re-check if an interface change moves it.
3. Go to the plugins area for developer mode connectors and select the plus button to create a new one.
4. Enter a user facing name, for example Fine Structure, and a short description such as: builds, edits and publishes web apps.
5. Under Connection, choose the public endpoint option and enter https://finestructure.ai/api/mcp as the MCP server URL. Do not enter the site root, because the MCP endpoint is the /api/mcp path.
6. Create the connection, then review the discovered tools and metadata that ChatGPT lists back to you.
7. Complete the OAuth sign in when prompted. Fine Structure supports dynamic client registration, so there is nothing to paste.
8. Open a new chat, select the developer mode tool in the composer, and ask it to list your Fine Structure apps to confirm the connection.

What to watch out for

• OpenAI classes developer mode connectors as elevated risk and requires confirmation for write actions by default. A tool without a read only hint is treated as a write action, so publishing and file edits will ask before running.
• A remembered confirmation applies to that conversation only. A new chat asks again.
• OpenAI documents both streamable HTTP and SSE for this surface, and Fine Structure serves streamable HTTP at the URL above.
• This is a developer mode surface rather than a reviewed app listing, so it does not appear in the ordinary ChatGPT apps directory. Everyone who wants it connects it themselves.
• The difference from Claude is friction rather than capability: the same roughly 70 tools, reached through developer mode and with more per action confirmations.
• OpenAI also documents a Secure MCP Tunnel for private servers under development. Fine Structure is a public HTTPS endpoint, so pick the public endpoint option.

Questions people ask

Does this work on ChatGPT Free?

OpenAI's developer mode guide lists Pro, Plus, Business, Enterprise and Education accounts, and does not list Free. If you are on a free account you will most likely need to upgrade, or use a client such as Claude, Le Chat or VS Code Copilot that does not gate remote MCP behind a paid tier.

Why does ChatGPT ask permission every time it publishes?

Because OpenAI treats any tool without a read only hint as a write action and requires confirmation by default. It is a ChatGPT policy rather than a Fine Structure setting, and you can remember the choice for the current conversation.

My workspace admin disabled developer mode. What now?

Ask the administrator to allow connector creation, since that toggle is on their side. Otherwise connect Fine Structure from a personal client and keep the work in the same Fine Structure account.

Vendor documentation we checked

• https://developers.openai.com/api/docs/guides/developer-mode
• https://developers.openai.com/plugins/deploy/connect-chatgpt
• https://finestructure.ai/api/mcp/docs

All platforms: connect Fine Structure to any AI. Also the documentation and pricing.