AI agents use unmerge_cells to create or update resources in DOCX-MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your DOCX-MCP environment.
Unmerging cells is a reversible modification to document structure. It changes the layout and formatting of a table but does not delete data or trigger external operations. This places it in the Write category. Severity is medium because while the change is reversible, careless unmerging could corrupt table structure or alter document formatting in ways that require careful repair.
From the tool's definition Tool name 'unmerge_cells' indicates modification of table cell structure in Word documents. Sibling tools on the server include 'merge_cells', 'delete_table_rows', 'add_table_columns', 'add_table_rows', 'create_table', 'delete_table', all of which are Write…
Documented attack patterns abuse exactly the kind of access unmerge_cells gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and DOCX-MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for unmerge_cells:
{
"version": "1",
"default": "deny",
"tools": {
"unmerge_cells": {
"limits": [
{
"counter": "unmerge_cells_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}unmerge_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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unmerge_cells. It is categorised as a Write tool in the DOCX-MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the DOCX- MCP server in PolicyLayer and add a rule for unmerge_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 DOCX-MCP. Nothing to install.
unmerge_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 unmerge_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 unmerge_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.
unmerge_cells is provided by the DOCX- MCP server (rookie0x80/docx-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from DOCX-MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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16 DOCX-MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.