print · Rr MCP: Risk & Policy

WHAT IT DOES

What print does on Rr

AI agents invoke print 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 print needs a policy

The tool evaluates arbitrary expressions in the debugging session context. While it may primarily read values, expression evaluation in a debugger can have side effects (e.g., calling functions, modifying state through expressions with assignments). 'Evaluate any expression' implies arbitrary code execution capability, making this Execute rather than Read.

From the tool's definition Evaluate any expression in the current context and return its value

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

print Rate-limited

print 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": {
    "print": {
      "limits": [
        {
          "counter": "print_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 print

What does the print tool do? +

Evaluate any expression in the current context and return its value. 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 print? +

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

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

Can I rate-limit print? +

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

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

print 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.