set_calculated_property · Melo MCP: Risk & Policy

WHAT IT DOES

What set_calculated_property does on Melo

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

WHY IT NEEDS A POLICY

Why set_calculated_property needs a policy

This tool modifies instance properties in Roblox Studio through calculated formulas, making it a Write category tool. It creates or alters data reversibly—properties can be changed again or reverted. It is not Destructive (no deletion), Execute (no arbitrary code execution, though formulas are evaluated), or Read-only.

From the tool's definition Tool description states 'Set a property using a formula', which is a modification operation. The name 'set_calculated_property' indicates writing/updating data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_calculated_property Rate-limited

set_calculated_property 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_calculated_property": {
      "limits": [
        {
          "counter": "set_calculated_property_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Melo, so you can run agents against it safely.

FAQ

Questions about set_calculated_property

What does the set_calculated_property tool do? +

Set a property using a formula. The formula can reference the current value. Args: - path (string): Instance path - property (string): Property name - formula (string): Formula (e.g. It is categorised as a Write tool in the Melo 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_calculated_property? +

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

What risk level is set_calculated_property? +

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

Can I rate-limit set_calculated_property? +

Yes. Add a rate_limit block to the set_calculated_property 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_calculated_property completely? +

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

set_calculated_property is provided by the Melo MCP server (yannyhl/linkedsword-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.