How to Connect Claude to Your Inventory with MCP

To connect Claude to your inventory with MCP, add your inventory software's MCP server URL as a custom connector in Claude, sign in to the inventory software when Claude asks, and click Authorize. After that, Claude can read your coins, invoices, and reports and make changes you ask for, with the same permissions as your own account. ChatGPT, Claude Code, and Codex connect the same way with their own setup steps.

This guide explains what MCP is, how the connection works, the setup steps for each assistant, what to ask once you are connected, and how to keep it safe.

What is an MCP server?

MCP, the Model Context Protocol, is an open standard for connecting AI assistants to other software. The software runs an MCP server. The assistant is the MCP client. The server tells the client which tools exist, such as "list coins" or "create an invoice," and what input each one takes. When you ask a question, the assistant decides which tools to call, calls them, and answers from what comes back.

Without MCP, you copy data out of your inventory, paste it into a chat, and copy the answer back. With MCP, the assistant reads the live data and can write the change itself.

Local and remote servers

Some MCP servers run on your own computer. Inventory software usually runs a remote server: a URL on the internet. Claude, ChatGPT, Claude Code, and Codex can all connect to remote servers. A remote server needs a way to know who you are, which is where OAuth comes in.

How sign-in works: OAuth, not API keys

There are two common ways an MCP server can know who is calling:

	API key	OAuth
How you connect	Copy a secret key into the assistant	Sign in and click Authorize
Where the secret lives	In the assistant's settings, often pasted by hand	A token the assistant stores, never shown to you
Whose permissions	Whatever the key was given	Your own account's
How you remove access	Delete the key	Revoke the connected app

OAuth is the safer choice for a person. You never handle a long-lived secret, and the assistant can do only what your account can do. If a staff member connects their assistant, it gets their permissions, not the owner's.

How to connect Claude to your inventory with MCP

The exact menu names change as the assistants update their apps, so check each assistant's own help pages if a step does not match. The flow stays the same: add the URL, sign in, authorize.

Claude (claude.ai and the desktop app)

1. Open Settings, then Connectors.
2. Add a custom connector and paste the MCP server URL.
3. Click Connect. Sign in to your inventory software and click Authorize.

ChatGPT

1. In the settings for apps and connectors, turn on developer mode.
2. Create a connector, paste the MCP server URL, and choose OAuth.
3. Sign in to your inventory software and click Authorize.

Claude Code

Run the add command in a terminal, then sign in from inside Claude Code:

claude mcp add --transport http <name> <server URL>

Then type /mcp in Claude Code and sign in.

Codex

codex mcp add <name> --url <server URL>
codex mcp login <name>

What to ask once you are connected

Ask the way you would ask an employee who knows the system. Some requests that work well:

• "What was my profit on eBay last month?"
• "Which invoices are unpaid, and which are past due?"
• "List the coins that have been in stock for more than a year, with their cost."
• "Change the price of the 1921-D Morgan dollar to $500."
• "Which consignments still have unsold coins?"
• "Draft a workflow that posts each paid sale to Slack."

A worked example

You ask: "What was my profit on eBay in October?"

The assistant finds the reports tools, reads the profit report for October 1 to October 31 filtered to eBay, and gets back revenue of $12,480.00, coin cost of $8,960.00, and eBay fees of $1,640.00. It answers:

Profit was $1,880.00 on $12,480.00 of revenue, a 15.1% margin.

The arithmetic: $12,480.00 − $8,960.00 − $1,640.00 = $1,880.00, and $1,880.00 ÷ $12,480.00 = 15.1%. The assistant did not estimate anything. It read the numbers your software already keeps.

Questions that work less well

• Questions about data the software does not have. If you never recorded cost, there is no profit to report.
• Questions that need judgment the data cannot give, such as "Is this coin undergraded?" without photos or grading data.
• Very large exports. Ask for a summary or a filtered list, or export a CSV from the app.

How to keep it safe

An assistant that can change data needs the same care as a new employee with a login.

• Check the permissions model. The server should act as you, with your permissions. Avoid servers that give every connection full access.
• Look for closed areas. Sign-in, team membership, API keys, billing, and permission settings should not be changeable through an assistant.
• Confirm changes. A good server tells the assistant to state each change and wait for your yes. Read the confirmation before you agree.
• Know how to revoke. Find the connected apps page in your inventory software before you need it.
• Mind credits and costs. Actions that cost money in the app, such as AI valuations, usually cost the same through an assistant.

Common mistakes

• Connecting with the owner's account for the whole team. Each person should connect with their own login so permissions and history stay correct.
• Asking for everything at once. "Show me all my coins" on a large inventory returns pages of data. Ask a narrower question.
• Agreeing to a change without reading it. The confirmation is there to catch the wrong coin or the wrong price.
• Forgetting old connections. Revoke assistants you no longer use.

How CoinManagerPro does this

The CoinManagerPro MCP server connects Claude, ChatGPT, Claude Code, Codex, and other MCP clients with OAuth. You sign in with your CoinManagerPro account; there is no API key to copy.

• Four tools reach the app's operations: find_operations, describe_operation, read, and change. The assistant finds the operation it needs, reads its input, then reads or changes data.
• The assistant has your permissions in the workspace. A member without permission to see cost cannot get cost through it.
• It cannot change sign-in, your team, API keys, connected apps, integration credentials, billing, or member permissions. It can read billing and permissions.
• It can draft a workflow for you to review and activate in the app.
• A workspace without an active plan is read only.
• To remove access, go to Settings, Connected apps, and click Revoke. The assistant stops at its next request.

The connector URL and the setup steps for each assistant are on the developers page. If you would rather not use another app, the in-app assistant answers the same kinds of questions inside CoinManagerPro.