mass_set_property · Melo MCP: Risk & Policy

WHAT IT DOES

What mass_set_property does on Melo

AI agents use mass_set_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 mass_set_property needs a policy

This tool creates or modifies data reversibly across multiple Roblox instances in a batch transaction. While the atomic all-or-nothing guarantee is valuable for safety, the tool itself performs Write operations (property modification).

From the tool's definition Tool description states "Set the same property on multiple instances atomically" with "All-or-nothing" semantics. The args show it modifies properties on multiple instances via `paths`, `property`, and `value` parameters.

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mass_set_property Rate-limited

mass_set_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": {
    "mass_set_property": {
      "limits": [
        {
          "counter": "mass_set_property_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 Melo, so you can run agents against it safely.

FAQ

Questions about mass_set_property

What does the mass_set_property tool do? +

Set the same property on multiple instances atomically. All-or-nothing. Args: - paths (string[]): Instance paths - property (string): Property name - value (any): Value to set Returns: Count of updated instances. 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 mass_set_property? +

Register the Melo MCP server in PolicyLayer and add a rule for mass_set_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 mass_set_property? +

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

Can I rate-limit mass_set_property? +

Yes. Add a rate_limit block to the mass_set_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 mass_set_property completely? +

Set action: deny in the PolicyLayer policy for mass_set_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 mass_set_property? +

mass_set_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.