AI agents use merge_cells to create or update resources in Office Editor — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Office Editor environment.
Merging cells in Excel/Word is a reversible formatting operation that modifies document structure but does not delete data irreversibly or execute arbitrary code. This qualifies as Write rather than Destructive. Severity is medium because while reversible, a misbehaving AI could corrupt document layout or make data harder to access.
From the tool's definition Tool is named 'merge_cells' and belongs to office-editor-mcp server for editing Excel and other Office documents.
Documented attack patterns abuse exactly the kind of access merge_cells gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Office Editor, and nothing reaches the server without passing your rules. This is the rule we recommend for merge_cells:
{
"version": "1",
"default": "deny",
"tools": {
"merge_cells": {
"limits": [
{
"counter": "merge_cells_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}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.
Free to start. No card required.
merge_cells. It is categorised as a Write tool in the Office Editor MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Office Editor MCP server in PolicyLayer and add a rule for 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 Office Editor. Nothing to install.
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 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 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.
merge_cells is provided by the Office Editor MCP server (thewdy/office-editor-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 88 Office Editor tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
88 Office Editor tools catalogued and risk-classified — across an index of 42,500+ MCP servers.