catch · Rr MCP: Risk & Policy

WHAT IT DOES

What catch does on Rr

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

WHY IT NEEDS A POLICY

Why catch needs a policy

This tool creates a new catchpoint in the debugger session, which is a write/configuration action (modifying debugger state). It does not execute code, delete data, or involve finances. It is reversible as catchpoints can be removed. Severity is medium because misconfiguration could disrupt a debugging session but has limited blast radius beyond the debug environment.

From the tool's definition Set a catchpoint to break on C++ exceptions or syscalls

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

catch Rate-limited

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

FAQ

Questions about catch

What does the catch tool do? +

Set a catchpoint to break on C++ exceptions or syscalls. It is categorised as a Write tool in the Rr MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on catch? +

Register the Rr MCP server in PolicyLayer and add a rule for catch: 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 catch? +

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

Can I rate-limit catch? +

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

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

catch 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.