update_sheet_values_tool

THE RISK

Medium Risk

Why update_sheet_values_tool needs a policy

This tool creates or modifies data reversibly in a spreadsheet context. While the description is empty (lowering confidence slightly), the name clearly indicates it updates sheet values, which is a Write operation. The severity is medium because unauthorized modification of shared spreadsheet data could impact multiple users and business processes, but the changes are reversible (unlike Destructive operations).

From the tool's definition Tool name 'update_sheet_values_tool' indicates modification of spreadsheet data. The 'update' verb and 'values' object confirm it writes/modifies data in Google Sheets rather than merely reading it.

Documented attack patterns abuse exactly the kind of access update_sheet_values_tool gives an agent:

POLICY

How to control update_sheet_values_tool

PolicyLayer is an MCP gateway — it sits between your AI agents and Apps Script MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for update_sheet_values_tool:

policy.json

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

update_sheet_values_tool 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.

Create a free account and register Apps Script MCP — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

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All 60 Apps Script MCP tools →

Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about update_sheet_values_tool

What does the update_sheet_values_tool tool do? +

update_sheet_values_tool. It is categorised as a Write tool in the Apps Script MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_sheet_values_tool? +

Register the Apps Script MCP server in PolicyLayer and add a rule for update_sheet_values_tool: 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 Apps Script MCP. Nothing to install.

What risk level is update_sheet_values_tool? +

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

Can I rate-limit update_sheet_values_tool? +

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

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

update_sheet_values_tool is provided by the Apps Script MCP server (sam-ent/google-automation-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Apps Script MCP tool call.

Start from Apps Script MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →