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The MCP page in Data Depot shows you how to connect an AI assistant to Cedar ARMS through the Model Context Protocol (MCP). Once connected, you can ask the assistant questions such as “How many loaded cars are at Quillmoor Junction?” and it looks up the answer in ARMS for you.
  • Uses your own login. You sign in with your Cedar account when the assistant first connects. There is no separate key to create or share.
  • Read-only. The assistant can list and look up ARMS data. It can’t create, update, move, or delete anything; those changes stay in the ARMS app.
  • Your permissions apply. The assistant can see only what you can see in ARMS, for the carriers you have access to.
Connect MCP page with the starter prompt preview and ChatGPT setup card

The Connect tab, with the starter prompt and setup for each AI app

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Connect your AI app

Every app connects to the same server URL:
Open MCP in the sidebar and find your app on the Connect tab.⁠​‌​​‌​‌​‌​‌‌‌​​‌​​​‌‌​​​⁠ Each card has copy buttons for the exact configuration. After you add the server, your app opens a Cedar sign-in page; sign in to finish connecting.
Setup cards for ChatGPT and Codex, Claude, and Cursor

Setup cards for each supported app

Add this to ~/.codex/config.toml (shared by ChatGPT desktop, Codex CLI, and the IDE extension):
Or run:
Then open Settings → MCP servers and complete Cedar sign-in when prompted.

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Start with the starter prompt

Select Copy starter prompt and paste it into a new chat after you connect. It tells the assistant how to use Cedar correctly:
  • check which carriers you can access first, and always say which carrier (by reporting mark) it is asking about;
  • never guess a carrier or make up data when access is denied;
  • page through large results, such as railcar inventory, instead of asking for everything at once.
The same guide is available inside the connection, so the assistant can look it up on its own.

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See what your assistant can do

The Permissions tab lists the read-only actions an assistant can take for the selected carrier, based on the user groups’ ARMS permissions.⁠​‌​​‌​‌​‌​‌‌‌​​‌​​​‌‌​​​⁠ Different people can see different actions.
Permissions tab with the user group filter, MCP action count, and Railcar actions

The Permissions tab lists MCP actions by API family

  • Use User groups to see the actions available to one or more groups. The count on the right shows how many MCP actions that adds up to.
  • Actions are grouped by API family. Each one shows its method and path, with a Docs link to the API reference.
  • Other ARMS actions (not MCP) lists operations that exist in the API but aren’t available through MCP, because they change data.
This tab only shows existing access. It doesn’t grant anything. To change what someone can do, change their ARMS roles in the Admin Portal.
The MCP pages don’t need a Data Depot role, and the carrier list on these pages includes every carrier you can access. To protect privacy, Cedar leaves some details out of what it returns to the assistant, such as street addresses, email addresses, and phone numbers. See MCP data handling.

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Troubleshooting

The assistant can only do what your ARMS permissions allow for that carrier.⁠​‌​​‌​‌​‌​‌‌‌​​‌​​​‌‌​​​⁠ Check the Permissions tab, and ask your administrator if you need more access.
If you can access more than one carrier, name the carrier by its reporting mark in your question, for example “Show inventory for DEMO”.
This connection is read-only. Make changes in the ARMS app.
MCP may not be turned on for your account yet. Contact your Cedar account team.