modify-variable · Debugger MCP Server MCP: Risk & Policy

WHAT IT DOES

What modify-variable does on Debugger MCP Server

AI agents invoke modify-variable to trigger actions in Debugger MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why modify-variable needs a policy

This tool mutates live program state by modifying variable values in a running application's scope. While not purely destructive (changes may be transient), it executes a state-altering operation in the runtime environment that can affect program behavior unpredictably. It goes beyond a Write (which implies data persistence) into Execute territory since it manipulates a live process's memory/scope.

From the tool's definition "Modify variable values in a specific scope" — actively changes runtime state in a live debugging session

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

modify-variable Rate-limited

modify-variable stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "modify-variable": {
      "limits": [
        {
          "counter": "modify-variable_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about modify-variable

What does the modify-variable tool do? +

Modify variable values in a specific scope. It is categorised as a Execute tool in the Debugger MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on modify-variable? +

Register the Debugger MCP Server MCP server in PolicyLayer and add a rule for modify-variable: 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 Debugger MCP Server. Nothing to install.

What risk level is modify-variable? +

modify-variable is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit modify-variable? +

Yes. Add a rate_limit block to the modify-variable 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 modify-variable completely? +

Set action: deny in the PolicyLayer policy for modify-variable. 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 modify-variable? +

modify-variable is provided by the Debugger MCP Server MCP server (phoenixrr2113/debugger-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.