You have built the agent. It calls a spreadsheet via API, reads the relevant cells, and produces something useful: a variance analysis, a scenario update, a summary for a board meeting. It works. Until you change the spreadsheet layout. Or until you start a new session and have to explain the model structure all over again. Or until the agent produces a number that is technically correct from the cell values it read, but violates a convention you have maintained for three years without anyone knowing to encode it.
Connecting an AI agent to a spreadsheet is a reasonable first step. It is not a model layer. And the difference turns out to matter a lot for anything you would call real financial work.
What spreadsheet access actually gives an agent
When an agent reads a spreadsheet (through an API, a plugin, or a code execution tool), it gets cells. It can read values, detect patterns in ranges, and make inferences about structure from formatting and proximity. That is more than nothing.
What it does not get:
