AI agents use modify_cell to create or update resources in Docx — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Docx environment.
The tool modifies cell content within Word document tables. This is a reversible write operation—the changes can be undone or overwritten. It does not delete data (would be Destructive), execute arbitrary code (would be Execute), or move money (would be Financial). The empty description lowers confidence slightly, but the name and server context provide sufficient indication of write-class functionality.
From the tool's definition Tool name 'modify_cell' combined with server context showing 'editing' Word documents and sibling tools like 'add_comment', 'add_bookmark', 'add_content_control' that perform reversible modifications.
Documented attack patterns abuse exactly the kind of access modify_cell gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Docx, and nothing reaches the server without passing your rules. This is the rule we recommend for modify_cell:
{
"version": "1",
"default": "deny",
"tools": {
"modify_cell": {
"limits": [
{
"counter": "modify_cell_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}modify_cell 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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modify_cell. It is categorised as a Write tool in the Docx 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 modify_cell: 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. Nothing to install.
modify_cell 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 modify_cell 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 modify_cell. 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.
modify_cell is provided by the Docx MCP server (securityronin/docx-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Docx, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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219 Docx tools catalogued and risk-classified — across an index of 43,000+ MCP servers.