start_replay_session · gdb and rr Debugging MCP

WHAT IT DOES

What start_replay_session does on gdb and rr Debugging

AI agents invoke start_replay_session to trigger actions in gdb and rr Debugging. 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 start_replay_session needs a policy

This tool triggers execution of an external system (rr replay), which is a debugger operation that can inspect and control program state. While it does not directly delete data or move money, it executes operations whose side effects depend on subsequent debugging commands and the specific trace being replayed.

From the tool's definition Tool 'start_replay_session' initiates an rr (record and replay) debugging session, enabling time-travel debugging capabilities.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_replay_session Rate-limited

start_replay_session 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": {
    "start_replay_session": {
      "limits": [
        {
          "counter": "start_replay_session_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 gdb and rr Debugging, so you can run agents against it safely.

FAQ

Questions about start_replay_session

What does the start_replay_session tool do? +

Start an rr replay session for time-travel debugging. It is categorised as a Execute tool in the gdb and rr Debugging MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on start_replay_session? +

Register the gdb and rr Debugging MCP server in PolicyLayer and add a rule for start_replay_session: 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 gdb and rr Debugging. Nothing to install.

What risk level is start_replay_session? +

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

Can I rate-limit start_replay_session? +

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

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

start_replay_session is provided by the gdb and rr Debugging MCP server (schuay/gdb-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.