step_to_prev_hit · Pernosco MCP: Risk & Policy

WHAT IT DOES

What step_to_prev_hit does on Pernosco

AI agents invoke step_to_prev_hit to trigger actions in Pernosco. 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 step_to_prev_hit needs a policy

This tool triggers navigation within a debugging session, changing the current execution state/position. It is an active operation (navigating/controlling a debugger) rather than a passive read, making it Execute. Misuse could confuse debugging context but has limited blast radius.

From the tool's definition Navigate backward to the previous execution of the current source line... Useful for reverse debugging

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

step_to_prev_hit Rate-limited

step_to_prev_hit 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": {
    "step_to_prev_hit": {
      "limits": [
        {
          "counter": "step_to_prev_hit_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 Pernosco, so you can run agents against it safely.

FAQ

Questions about step_to_prev_hit

What does the step_to_prev_hit tool do? +

Navigate backward to the previous execution of the current source line (or a specified line). Useful for reverse debugging. It is categorised as a Execute tool in the Pernosco MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on step_to_prev_hit? +

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

What risk level is step_to_prev_hit? +

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

Can I rate-limit step_to_prev_hit? +

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

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

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