Use AI to fill cells based on a pattern (Creator Studio only). Provide example values in the first rows of a column, then specify the range of empty cells to fill. Magic Fill detects the pattern and fills the remaining cells automatically.
AI agents use numbers_magic_fill 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 creates or modifies data in a reversible manner (filled cells can be cleared or edited). While it uses AI pattern detection, the fundamental operation is writing data to spreadsheet cells.
From the tool's definition Tool modifies spreadsheet data by automatically filling cells in a column based on pattern detection. Description states it 'fills cells' and 'fills the remaining cells automatically', which are write operations that create/modify cell contents.
Documented attack patterns abuse exactly the kind of access numbers_magic_fill 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_magic_fill:
{
"version": "1",
"default": "deny",
"tools": {
"numbers_magic_fill": {
"limits": [
{
"counter": "numbers_magic_fill_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}numbers_magic_fill 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.
Free to start. No card required.
Use AI to fill cells based on a pattern (Creator Studio only). Provide example values in the first rows of a column, then specify the range of empty cells to fill. Magic Fill detects the pattern and fills the remaining cells automatically. 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_magic_fill: 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_magic_fill 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_magic_fill 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_magic_fill. 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_magic_fill 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.