create_workbook · Excel MCP Server MCP: Risk & Policy

WHAT IT DOES

What create_workbook does on Excel MCP Server

AI agents use create_workbook 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 create_workbook needs a policy

This tool creates a new workbook, which is a write operation (data creation). It does not execute arbitrary code, destroy existing data, or move money. The severity is low because creating an empty workbook has minimal blast radius; the workbook exists only in memory until explicitly saved or manipulated by other tools.

From the tool's definition Tool description states 'Create a new Excel workbook in memory' — this is a create operation that produces new data structures reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_workbook Rate-limited

create_workbook 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": {
    "create_workbook": {
      "limits": [
        {
          "counter": "create_workbook_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 create_workbook

What does the create_workbook tool do? +

Create a new Excel workbook in memory. Returns a workbook ID to use with other tools. 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 create_workbook? +

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

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

Can I rate-limit create_workbook? +

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

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

create_workbook is provided by the Excel MCP Server MCP server (jauinones/xlsx-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.