Apply multiple formatting rules to different cell ranges in one call. More efficient than calling numbers_format_cells repeatedly.
AI agents use numbers_format_range 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.
The tool manipulates spreadsheet formatting properties, which is a Write-category operation (creates or modifies data reversibly). While formatting changes are easily reversible via undo, they could affect document appearance and integrity if applied maliciously to large ranges or critical spreadsheets.
From the tool's definition Tool applies "formatting rules to different cell ranges" - a reversible modification of spreadsheet data. The description explicitly states it modifies cell formatting (e.g., colors, fonts, styles), not data values.
Documented attack patterns abuse exactly the kind of access numbers_format_range 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_format_range:
{
"version": "1",
"default": "deny",
"tools": {
"numbers_format_range": {
"limits": [
{
"counter": "numbers_format_range_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}numbers_format_range 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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Apply multiple formatting rules to different cell ranges in one call. More efficient than calling numbers_format_cells repeatedly. 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_format_range: 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_format_range 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_format_range 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_format_range. 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_format_range 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.
Free to start. No card required.
114 Iwork tools catalogued and risk-classified — across an index of 43,000+ MCP servers.