AI agents use excel_add_worksheet to create or update resources in Sage MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Sage MCP environment.
This tool creates a new worksheet within an Excel workbook, which is a write operation that modifies data/structure reversibly. It does not execute arbitrary code, delete data, involve financial transactions, or trigger external side effects. The severity is low because adding a worksheet has minimal blast radius—it does not overwrite existing data, affect other systems, or cause irreversible harm.
From the tool's definition Tool name 'excel_add_worksheet' and description 'Add a new worksheet (tab) to an existing workbook' indicate creation of a new worksheet, which is a reversible modification to a spreadsheet structure.
Documented attack patterns abuse exactly the kind of access excel_add_worksheet gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Sage MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for excel_add_worksheet:
{
"version": "1",
"default": "deny",
"tools": {
"excel_add_worksheet": {
"limits": [
{
"counter": "excel_add_worksheet_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}excel_add_worksheet 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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Add a new worksheet (tab) to an existing workbook. It is categorised as a Write tool in the Sage MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Sage MCP server in PolicyLayer and add a rule for excel_add_worksheet: 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 Sage MCP. Nothing to install.
excel_add_worksheet 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 excel_add_worksheet 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 excel_add_worksheet. 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.
excel_add_worksheet is provided by the Sage MCP server (sagemcp/sagemcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 359 Sage MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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359 Sage MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.