set_cell · Ironcalc MCP: Risk & Policy

WHAT IT DOES

What set_cell does on Ironcalc

AI agents use set_cell to create or update resources in Ironcalc — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Ironcalc environment.

WHY IT NEEDS A POLICY

Why set_cell needs a policy

An AI agent can call set_cell faster than any human can review — one bad instruction and it creates or modifies resources in Ironcalc by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_cell Rate-limited

set_cell 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": {
    "set_cell": {
      "limits": [
        {
          "counter": "set_cell_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 Ironcalc, so you can run agents against it safely.

FAQ

Questions about set_cell

What does the set_cell tool do? +

Set a single cell's value. Use '=' prefix for formulas. It is categorised as a Write tool in the Ironcalc MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_cell? +

Register the Ironcalc MCP server in PolicyLayer and add a rule for set_cell: 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 Ironcalc. Nothing to install.

What risk level is set_cell? +

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

Can I rate-limit set_cell? +

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

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

set_cell is provided by the Ironcalc MCP server (yolonir/ironcalc-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.