set_selection · Melo MCP: Risk & Policy

WHAT IT DOES

What set_selection does on Melo

AI agents use set_selection 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_selection needs a policy

This is a Write operation because it modifies application state (the selection) reversibly—users can change the selection again or deselect. It is not Read (which would only query the current selection), nor Execute/Destructive (no code execution or irreversible data loss).

From the tool's definition The tool 'set_selection' modifies the current state of the Studio Explorer panel by changing which instances are selected.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_selection Rate-limited

set_selection 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_selection": {
      "limits": [
        {
          "counter": "set_selection_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 set_selection

What does the set_selection tool do? +

Set the current selection in the Studio Explorer panel. Args: - paths (string[]): Instance paths to select (min 1, max 100) Returns: Confirmation with selected paths. 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_selection? +

Register the Melo MCP server in PolicyLayer and add a rule for set_selection: 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_selection? +

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

Can I rate-limit set_selection? +

Yes. Add a rate_limit block to the set_selection 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_selection completely? +

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

set_selection 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.