add_formula · Excel MCP Server MCP: Risk & Policy

WHAT IT DOES

What add_formula does on Excel MCP Server

AI agents use add_formula 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 add_formula needs a policy

Adding a formula to a cell modifies spreadsheet data, but does not irreversibly destroy it or execute arbitrary external code. While formulas can perform calculations, the tool itself is classified as Write because it creates/modifies data within the spreadsheet.

From the tool's definition Tool description in Japanese translates to 'Add a formula to a cell.' This creates or modifies cell content with formulas, which is reversible via overwriting.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_formula Rate-limited

add_formula 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": {
    "add_formula": {
      "limits": [
        {
          "counter": "add_formula_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 add_formula

What does the add_formula tool do? +

セルに数式を追加します. 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 add_formula? +

Register the Excel MCP Server MCP server in PolicyLayer and add a rule for add_formula: 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 add_formula? +

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

Can I rate-limit add_formula? +

Yes. Add a rate_limit block to the add_formula 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 add_formula completely? +

Set action: deny in the PolicyLayer policy for add_formula. 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 add_formula? +

add_formula 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.