Create a chart from table data. Selects the specified data range and creates a chart on the same sheet. Chart type can be set after creation.
AI agents use numbers_add_chart 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.
This tool creates new content (a chart) within a spreadsheet document, making it a Write operation. It does not execute arbitrary code, delete data, move money, or perform irreversible actions. Severity is medium because charts are typically reversible (can be deleted), and the blast radius is limited to spreadsheet content modification. The high confidence reflects clear language indicating creation of a new object.
From the tool's definition Tool description states it 'creates a chart' on a sheet, which is a create/modify data operation. The tool adds a new object (chart) to a Numbers spreadsheet document.
Documented attack patterns abuse exactly the kind of access numbers_add_chart 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_add_chart:
{
"version": "1",
"default": "deny",
"tools": {
"numbers_add_chart": {
"limits": [
{
"counter": "numbers_add_chart_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}numbers_add_chart 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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Create a chart from table data. Selects the specified data range and creates a chart on the same sheet. Chart type can be set after creation. 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_add_chart: 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_add_chart 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_add_chart 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_add_chart. 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_add_chart 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.