How to Connect ChatGPT to OnePlan Using the MCP Server

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Direct Answer: How to Connect ChatGPT to OnePlan Using the MCP Server

To connect ChatGPT to OnePlan, go to ChatGPT Plugins, select Add > Add custom MCP server, enter the OnePlan MCP Server address for your region, set Registration method to User Defined OAuth Client, and copy the Callback URL that ChatGPT generates. In OnePlan, create an app registration under profile avatar > Register Custom Apps with that callback URL. Paste the Client ID back into ChatGPT, select Create as a plugin, sign in to OnePlan, and make the plugin available to your workspace.

Note: The OnePlan MCP Server is available in preview to approved customers. To request access, contact your Customer Success Manager.

What This Article Covers: Connecting ChatGPT to OnePlan

This article explains how ChatGPT workspace administrators on Business, Enterprise, or Edu plans add OnePlan as a custom MCP plugin through the OnePlan MCP Server.

What you will accomplish By the end of this article, you will have registered ChatGPT as an app in OnePlan, added OnePlan as a custom MCP plugin in ChatGPT, and made it available to your workspace.

Before You Begin: Connecting ChatGPT to OnePlan

Before you begin, make sure you have:

  • OnePlan MCP Server preview access approved for your organization
  • A OnePlan group administrator to create the app registration
  • A ChatGPT Business, Enterprise, or Edu plan
  • The ChatGPT Create plugins with MCPs permission. On Business, only admins and owners have it. On Enterprise and Edu, admins can grant it with role-based access control.
  • The OnePlan MCP Server address for your region:
Region Server address
Global https://my.oneplan.ai/mcp
Canada https://ca.oneplan.ai/mcp
Australia https://au.oneplan.ai/mcp
Europe https://eu.oneplan.ai/mcp

Note: ChatGPT custom MCP plugins work on ChatGPT web only. For OpenAI’s own instructions, see Connecting custom MCP servers in ChatGPT.

Why This Matters: Connecting ChatGPT to OnePlan

Context: Why You Start in ChatGPT

ChatGPT generates a unique callback URL for each custom MCP plugin. You need that URL to create the OnePlan app registration, so setup starts in ChatGPT, moves to OnePlan, and finishes back in ChatGPT.

Context: ChatGPT Tool Snapshots

ChatGPT uses a snapshot of the OnePlan tools taken when the plugin was created or approved. When OnePlan releases new tools, they don’t appear in ChatGPT until you refresh the plugin.

Step-by-Step: Connecting ChatGPT to OnePlan

Task: Start the Plugin in ChatGPT and Copy the Callback URL

Starting from ChatGPT:

  1. Go to chatgpt.com/plugins.

  2. Select Add, then Add custom MCP server. ChatGPT Plugins page with the Add menu open and Add custom MCP server highlighted

  3. Enter the server details:

    • Name — OnePlan
    • Description (optional) — Search, read, and update OnePlan plans, resources, financials, work items, and approvals.
    • Connection — The OnePlan MCP Server address for your region
    • Authentication — OAuth

    ChatGPT Add custom MCP server dialog with the OnePlan name, description, and server address

  4. Open Advanced OAuth settings and set Registration method to User Defined OAuth Client. OnePlan doesn’t support dynamic client registration yet, so ChatGPT can’t register itself.

  5. Copy the Callback URL. It looks like https://chatgpt.com/connector/oauth/{unique-id}.

    ChatGPT Advanced OAuth settings showing the Registration method and the Callback URL copy button

Important: Keep this window open. If you close it or start a second draft, ChatGPT generates a new callback URL.

ChatGPT Advanced OAuth settings with the OnePlan Client ID and Client Secret entered

Task: Create an App Registration in OnePlan

In a new browser tab, follow How to Create an App Registration for the MCP Server in OnePlan with these values:

  • Application Name — ChatGPT
  • Callback URL(s) — The callback URL you copied from ChatGPT
  • Scope — Group, or Organization to share across groups
  • Public client — Select for no Client Secret, or leave cleared to create a Client Secret

Copy the Client ID (and Client Secret, if you created one).

Task: Finish the OAuth Settings in ChatGPT

Return to the ChatGPT tab and complete Advanced OAuth settings:

  • OAuth Client ID — From the OnePlan app registration
  • OAuth Client Secret — From the OnePlan app registration, or leave blank for a public client
  • Base scopes — Leave blank
  • Registration URL — Leave blank

ChatGPT fills in the remaining fields automatically, including Auth URL, Token URL, Authorization server base, Resource, and OIDC configuration URL. Confirm they use the same region as your server address.

Task: Create the Plugin and Sign In

Starting from the completed Advanced OAuth settings:

  1. Select I understand and want to continue.
  2. Select Create as a plugin.
  3. Select Continue to OnePlan, sign in, and choose your group.
  4. Review the tools ChatGPT discovered.

The plugin appears under Installed in chatgpt.com/plugins.

Task: Test the Plugin

Starting from ChatGPT:

  1. Select Try in chat, or start a new chat, type @, and select OnePlan.
  2. Ask: “List 5 plans I have access to in OnePlan.”

Task: Make OnePlan Available to Your Workspace

Starting from ChatGPT:

  1. Go to the ChatGPT Admin Console and select your workspace.
  2. Open Plugins, then select Manage Legacy Apps.
  3. Select Drafts, select OnePlan, then select Publish.
  4. Review the safety warnings, especially for tools that make changes, then confirm.

Only workspace admins and owners can publish. On Enterprise and Edu plans, use Configure Actions in the publish window to choose which OnePlan tools are allowed, and Configure Access to choose who can use the plugin. To start read-only, leave tools that make changes turned off. For a list of which tools are read-only, see MCP Server in OnePlan - Overview.

Share How to Connect Your AI Assistant to OnePlan Using the MCP Server with your users.

Task: Refresh the Tool List

When OnePlan releases new tools:

  1. In Workspace settings > Apps, open the OnePlan app and refresh its tool list. You need permission to manage the app and a valid connection to it.
  2. On Enterprise and Edu plans, select the more options menu (•••) next to the app, select Action control, and turn on new actions. New actions are off by default, and changes to existing actions are shown for review.

Task: Remove ChatGPT Access

  • To remove the plugin: remove OnePlan from chatgpt.com/plugins or Workspace settings > Apps.
  • To stop all ChatGPT sign-ins to OnePlan: in OnePlan, select Revoke on the app registration under Register Custom Apps.

Frequently Asked Questions: Connecting ChatGPT to OnePlan

Q: Why didn’t ChatGPT show a callback URL? A: In ChatGPT, make sure Registration method is set to User Defined OAuth Client. If the callback URL still doesn’t appear, create the OnePlan app registration with https://localhost, then edit it with the URL ChatGPT reports in the sign-in error.

Q: Can ChatGPT Pro users connect to OnePlan? A: Only with read and fetch permissions. Full MCP support in ChatGPT, including tools that make changes, is available on Business, Enterprise, and Edu workspaces.

Q: Why don’t new OnePlan tools appear in ChatGPT? A: ChatGPT uses a snapshot of the OnePlan tools. Open the OnePlan plugin and select Refresh. On Enterprise and Edu plans, also turn on new actions in Action control.

Q: Can I limit ChatGPT to read-only OnePlan tools? A: Yes, on ChatGPT Enterprise and Edu plans. When you publish the OnePlan plugin, use Configure Actions to leave tools that make changes turned off.

What to Do Next: Connecting ChatGPT to OnePlan

Get started with related tasks:

Learn about related topics:

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