format_cell · Excel MCP Server MCP: Risk & Policy

WHAT IT DOES

What format_cell does on Excel MCP Server

AI agents use format_cell to create or update resources in Excel MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Excel MCP Server environment.

WHY IT NEEDS A POLICY

Why format_cell needs a policy

format_cell modifies cell appearance properties (fonts, colors, borders) without altering underlying data or formulas. Formatting changes are reversible and do not destroy data or execute arbitrary code. This qualifies as Write category—a data modification tool with side effects that can be undone.

From the tool's definition Tool description indicates setting cell formatting (font, fill, borders) on spreadsheet cells. The Japanese text '書式（フォント、塗りつぶし、罫線）を設定します' translates to 'set formatting (font, fill, borders)'. This is a reversible modification of cell properties.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

format_cell Rate-limited

format_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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "format_cell": {
      "limits": [
        {
          "counter": "format_cell_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Excel MCP Server, so you can run agents against it safely.

FAQ

Questions about format_cell

What does the format_cell tool do? +

セルの書式（フォント、塗りつぶし、罫線）を設定します. It is categorised as a Write tool in the Excel MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on format_cell? +

Register the Excel MCP Server MCP server in PolicyLayer and add a rule for format_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 Excel MCP Server. Nothing to install.

What risk level is format_cell? +

format_cell is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit format_cell? +

Yes. Add a rate_limit block to the format_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.

How do I block format_cell completely? +

Set action: deny in the PolicyLayer policy for format_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.

What MCP server provides format_cell? +

format_cell is provided by the Excel MCP Server MCP server (superpyonchix/excel_mcp_server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.