Connect an AI assistant
In Claude, connect xellstorm from the connectors directory; in another AI assistant, add https://app.xellstorm.com/mcp as a connector. Sign in to xellstorm and allow the connection in the app. Then ask in plain words: the assistant marks the uncertain cells, sets their ranges, runs the simulation in your xellstorm tab and explains the results. Your workbook file stays on your computer.
What you need
- An AI assistant that supports MCP connectors with sign-in. xellstorm is in Claude’s connectors directory, made for Claude, including Claude in Excel, and for Claude Code. Other assistants that let you add a remote MCP server by its address connect the same way.
- An xellstorm account. You sign in with your e-mail address. The example models open without a license; your own workbooks open as they do without an assistant: free for learning and non-profits, with a trial or a license for work.
- The xellstorm app open in your browser. The assistant works through the app: it reads and changes the setup there, and simulations run in your browser, as they do when you choose Run simulation yourself.
Connect in three steps
- Add the connector. In Claude, find xellstorm in the connectors directory and choose Connect. In another assistant, add a custom connector with the address
https://app.xellstorm.com/mcp. - Sign in and allow. Your assistant opens xellstorm in your browser to ask for your permission. Sign in with your e-mail address if you have not yet, then choose Allow.
- Work in the app. Open your workbook, or an example, in xellstorm in the same browser, and keep the tab open while you ask. The assistant’s name shows at the top of the app while it is connected.
In Claude
Go to Customize > Connectors, find xellstorm in the directory and choose Connect. On Team and Enterprise plans, an Owner adds xellstorm for the organization under Organization settings > Connectors, and each member connects with their own account. Claude in Excel uses the connectors of your Claude account. In a chat, turn the connector on from + > Connectors.
In Claude Code, run claude mcp add --transport http xellstorm https://app.xellstorm.com/mcp, then sign in from /mcp.
What to ask
- “Which cells of this workbook look like assumptions? Set them up as ranges in xellstorm.”
- “Run 10,000 trials. What is the chance that the total cost goes over the budget?”
- “Which inputs drive the total cost the most?”
- “Fit a distribution to the lead times in column C and use it for the delivery time.”
- “Find the order quantity that gives the highest expected profit.”
- “Compare ordering 1,000, 1,100 and 1,200 units as scenarios. What would a better demand forecast be worth?”
- “Export the results as PowerPoint slides.”
The assistant can do what the app’s screens do: set inputs and outputs, correlations, scenarios, cells held constant and run settings; fit distributions to data; convert @RISK, ModelRisk and Analytic Solver formulas; run simulations and optimizations; read results, their drivers, what more information would be worth when scenarios are choices, and earlier runs; and export results workbooks, reports and slides. Your browser saves exported files on your computer.
You stay in control
- Off until you allow it. No assistant can connect until you choose Allow in the app, and a browser answers only after you allowed a connection in it.
- Every change in view. Changes show in the app as they happen. Choose the assistant’s name at the top of the app to see each change it made.
- Undo where the app can. Changes to inputs and outputs can be undone with Ctrl+Z or Undo. Scenarios, correlations, cells held constant, run settings and optimizations cannot, so the assistant is asked to check with you before it removes or replaces what you set up.
- Formulas are kept. The assistant puts a distribution on a cell that holds a formula only when it says explicitly that it replaces the formula.
- Pause or disconnect. Under the assistant’s name, Pause in this browser stops this browser from answering, and Disconnect ends the connection at once.
What passes through our server
While an assistant is connected, what it asks for and the app’s answers pass through xellstorm’s server: the addresses, names, values and formulas of the cells it reads, your simulation setup and summaries of results. They are held in memory until the answer is delivered and are never stored. The workbook file, the trials of a run and the files you export stay on your computer. What reaches the assistant is handled by its provider. The Privacy Policy has the details.
Questions
The assistant says the app is not open.
Open the app in the browser where you allowed the connection, signed in with the same account. To work in another browser, sign in to the app there, open your account and choose Use this browser.
The assistant says my workbook has changed, or asks me to save it.
The app works on the last saved version of your workbook, while an assistant in Excel sees changes you have not saved yet. Save in Excel and open the new version in the app. In Chrome and Edge, choose to follow the file on disk after you open it, and the app reads each version you save.
The assistant says to reload the app.
The app in that tab is older than the connector. Reload the tab.
Which assistants work?
Any assistant that can add a remote MCP server by its address and sign in to it with OAuth. In Claude, xellstorm is in the connectors directory; the connector is made for Claude, including Claude in Excel, and for Claude Code.
Does the connector cost extra?
No. It comes with xellstorm on every plan.
How do I disconnect?
Choose the assistant’s name at the top of the app, then Disconnect. You can also remove the connector in your assistant’s settings.