write_range · Excel MCP Server MCP: Risk & Policy

WHAT IT DOES

What write_range does on Excel MCP Server

AI agents use write_range 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 write_range needs a policy

This tool creates or modifies cell values within a spreadsheet, which is reversible (can be undone or overwritten). It does not permanently delete data, execute arbitrary code, move money, or read-only retrieve information. The 'Write' category is appropriate. Severity is medium because misuse could corrupt important spreadsheet data, but the effects are limited to the specific workbook and are reversible.

From the tool's definition Tool name is 'write_range' and description explicitly states 'Write a 2D array of values to a range starting at a specific cell', indicating creation or modification of data in an Excel workbook.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

write_range Rate-limited

write_range 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": {
    "write_range": {
      "limits": [
        {
          "counter": "write_range_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 write_range

What does the write_range tool do? +

Write a 2D array of values to a range starting at a specific cell. 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 write_range? +

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

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

Can I rate-limit write_range? +

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

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

write_range 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.