Modify values in a specific range of a Google Sheet - can write, update, or clear values
AI agents use modify_sheet_values to create or update resources in VaultAssist — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your VaultAssist environment.
This tool creates or modifies data in Google Sheets in a reversible manner. While it can clear values, the description does not indicate permanent deletion of the sheet itself or irreversible destruction. The high severity reflects that an AI agent with unchecked access could corrupt important spreadsheet data across potentially many rows/columns, affecting multiple users in a Workspace environment.
From the tool's definition Tool description explicitly states it can 'write, update, or clear values' in a Google Sheet. The verb 'modify' combined with these capabilities confirms reversible data mutation.
Documented attack patterns abuse exactly the kind of access modify_sheet_values gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and VaultAssist, and nothing reaches the server without passing your rules. This is the rule we recommend for modify_sheet_values:
{
"version": "1",
"default": "deny",
"tools": {
"modify_sheet_values": {
"limits": [
{
"counter": "modify_sheet_values_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}modify_sheet_values 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.
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Modify values in a specific range of a Google Sheet - can write, update, or clear values. It is categorised as a Write tool in the VaultAssist MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the VaultAssist MCP server in PolicyLayer and add a rule for modify_sheet_values: 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 VaultAssist. Nothing to install.
modify_sheet_values is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the modify_sheet_values 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.
Set action: deny in the PolicyLayer policy for modify_sheet_values. 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.
modify_sheet_values is provided by the VaultAssist MCP server (3xcaffeine/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from VaultAssist, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
79 VaultAssist tools catalogued and risk-classified — across an index of 43,000+ MCP servers.