Merge a range of cells
AI agents use numbers_merge_cells to create or update resources in Iwork — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Iwork environment.
Merging cells is a Write operation because it modifies the spreadsheet structure in a way that can be undone (cells can be unmerged). While it affects data layout, it is not destructive (data is not deleted) and does not involve execution, financial transactions, or external code execution.
From the tool's definition Tool performs 'Merge a range of cells' which modifies cell structure in Numbers spreadsheet. This is a reversible data modification operation.
Documented attack patterns abuse exactly the kind of access numbers_merge_cells gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Iwork, and nothing reaches the server without passing your rules. This is the rule we recommend for numbers_merge_cells:
{
"version": "1",
"default": "deny",
"tools": {
"numbers_merge_cells": {
"limits": [
{
"counter": "numbers_merge_cells_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}numbers_merge_cells stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Merge a range of cells. It is categorised as a Write tool in the Iwork MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Iwork MCP server in PolicyLayer and add a rule for numbers_merge_cells: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Iwork. Nothing to install.
numbers_merge_cells is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the numbers_merge_cells rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for numbers_merge_cells. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
numbers_merge_cells is provided by the Iwork MCP server (reichenbach/iwork_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Iwork, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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