Ternary MCP for ChatGPT

This guide connects ChatGPT to your Ternary data. It applies to both chatgpt.com and the ChatGPT desktop app (macOS/Windows) — connectors belong to your ChatGPT account, so you set them up once and they work everywhere you're signed in, and the settings screens are the same in both. The mobile apps can use a connector you've already added, but adding one must happen on web or desktop.

In ChatGPT, custom MCP servers are added as plugins (ChatGPT's name for connectors), and what Ternary can do differs by mode:

This is a ChatGPT platform restriction, not a Ternary one: deep research connectors are limited by OpenAI to the search/fetch contract. For cost analysis, use developer mode.

Requirements

• A Ternary account (the email you use to sign in to Ternary).
• Developer mode enabled on your ChatGPT account (steps below). On Business/Enterprise/Edu workspaces, an admin may need to allow developer mode and custom plugins.

Step 1: Enable developer mode

Adding an unverified (custom) MCP server requires developer mode.

1. Open Settings → Security and login, and scroll to the Developer mode section — or use the Developer mode shortcut at the bottom of Settings → Plugins.
2. Turn the Developer mode toggle on. ChatGPT labels it "elevated risk" because it allows unverified servers; that warning is expected.

Step 2: Add Ternary as a plugin

1. Open the Plugins page from the left sidebar (or go to chatgpt.com/plugins).

2. Click Create app (top right — it only appears with developer mode on).

3. Fill in the New Plugin dialog:

   • Name: Ternary.
   • Connection: Server URL, with your region's server URL:
     • US: https://core-api.ternary.app/mcp
     • EU: https://core-api.eu.ternary.app/mcp
   • Authentication: OAuth (the default). Leave the advanced OAuth settings alone — they're discovered automatically.
   • Check the "I understand and want to continue" confirmation.

4. Click Create.

5. ChatGPT shows an Add Ternary to ChatGPT dialog — click Sign in with Ternary, log in with your Ternary credentials, and approve the access request.

The plugin's detail page now shows Connected on with the date.

Use it in a chat

1. Start a new chat.

2. Click the + button in the composer and pick Ternary from the menu to pin the plugin to your message.

3. Type your cost question, for example: "Which tenants can I access? Then show my top 5 services by spend for last month." — and send.

   You can also skip the menu and just mention Ternary in the prompt ("Using the Ternary plugin, …") — ChatGPT calls it automatically.

The Ternary tools that read your data run without confirmation prompts under the default Allow low-risk actions permission. Create report writes, so ChatGPT asks before it runs. ChatGPT lists your tenants, asks which one to query if needed, and reports the top services with the range total.

Good first prompts:

• "Which Ternary tenants can I access?"
• "Show my total cloud spend for last month, grouped by service."
• "Run a cost query for Q2 grouped by provider."

For deep research: start a Deep research run, add Ternary as a source, and ChatGPT will use search/fetch to pull in your saved reports as reference material.

OpenAI Codex (command line)

Codex is OpenAI's coding agent for the terminal. It connects to the same Ternary server as ChatGPT, but it is configured from the command line rather than the Plugins page, and it has no developer-mode step.

Codex needs version 0.148.0 or later. Earlier versions cannot sign in to Ternary.

codex mcp add ternary --url https://core-api.ternary.app/mcp

Use your region's URL: https://core-api.ternary.app/mcp for US, https://core-api.eu.ternary.app/mcp for EU.

That command detects the sign-in requirement and opens a Ternary page in your browser straight away. Log in and approve the access request. The session is remembered between runs.

If the browser does not open, or you need to sign in again later:

codex mcp login ternary

The equivalent entry in ~/.codex/config.toml, if you prefer to edit the file:

[mcp_servers.ternary]
url = "https://core-api.ternary.app/mcp"

Unlike ChatGPT's deep research mode, Codex has access to every Ternary tool.

Getting new Ternary tools

ChatGPT copies the list of Ternary tools (their names, descriptions, and parameters) when
you create the plugin, and does not check for changes on its own. When Ternary adds a tool
or changes an existing one, your plugin keeps the old list until you refresh it. This is how
ChatGPT plugins work for every MCP server, not something Ternary can change from its side.

Signs that your plugin is out of date:

• ChatGPT cannot find a tool that appears in the Available tools table on the overview page.
• ChatGPT says it cannot do something these docs say it can (for example, check budgets or
  compare a dashboard).
• You ask "Which Ternary tools do you have?" and the answer is shorter than the table.

To refresh the plugin:

1. Open Settings → Plugins and click Ternary.
2. Scroll to the Information block and click Refresh. ChatGPT re-reads the tool list
   from the Ternary server.
3. Start a new chat. A conversation that is already open keeps the tool list it started
   with.

If Refresh shows an error (for example "Reauthentication required"), or the tools do not
change, delete the plugin and create it again (Step 2 above). Reconnect in the plugin's
⋯ menu only signs you in again; it does not refresh the tool list. After re-creating the
plugin you sign in to Ternary once more; nothing else is lost.

Codex connects to the Ternary server each time it starts, so a new Codex session picks
up new tools on its own. If Codex reports the Ternary server as unauthorized, run
codex mcp login ternary again.

Troubleshooting

• No "Create app" button on the Plugins page — developer mode is off. Enable it under Settings → Security and login → Developer mode.
• Plugin creation fails — verify the exact URL including the /mcp path and the right region, then retry once (a first attempt can time out while the service warms up).
• Sign-in fails — your email must belong to an existing Ternary user in that region. US and EU accounts are separate.
• "No tenants found" — your Ternary user has no explicit role on any tenant. Ask your Ternary admin to grant you a role.
• A tool from these docs is missing, or ChatGPT behaves as an older version of these docs
  describes — your plugin holds an old copy of the tool list. Refresh it (see
  Getting new Ternary tools).
• Refresh fails with "Reauthentication required" — delete the plugin and create it
  again (Step 2). Reconnect does not fix this.
• Only search and fetch appear — you're in deep research mode, which is limited to those two tools. Ask in a regular chat with the Ternary plugin enabled instead.
• ChatGPT asks for confirmation on every tool call — expected for unverified plugins; you can allow per-conversation.