frame_select · Rr MCP: Risk & Policy

WHAT IT DOES

What frame_select does on Rr

AI agents invoke frame_select to trigger actions in Rr. 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 frame_select needs a policy

The tool switches the active stack frame in the debugger session, which is an action that modifies the session state (current frame context). While it doesn't execute code in the target program or modify data, it triggers a state change in the debugging session that affects subsequent operations. The description is truncated ('inspect its' is incomplete), lowering confidence slightly.

From the tool's definition 'Switch to a different stack frame' — actively changes the debugger's current execution context/state

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

frame_select Rate-limited

frame_select 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": {
    "frame_select": {
      "limits": [
        {
          "counter": "frame_select_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 Rr, so you can run agents against it safely.

FAQ

Questions about frame_select

What does the frame_select tool do? +

Switch to a different stack frame to inspect its. It is categorised as a Execute tool in the Rr MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on frame_select? +

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

What risk level is frame_select? +

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

Can I rate-limit frame_select? +

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

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

frame_select is provided by the Rr MCP server (jnjaeschke/rr-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.