start_test_session · Yo Bug MCP: Risk & Policy

WHAT IT DOES

What start_test_session does on Yo Bug

AI agents invoke start_test_session to trigger actions in Yo Bug. 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_test_session needs a policy

start_test_session triggers real processes with real consequences. An agent gone sideways doesn't fire it once — it starts dozens of builds, sends mass notifications, or burns through compute before anyone looks up.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_test_session Rate-limited

start_test_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_test_session": {
      "limits": [
        {
          "counter": "start_test_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 Yo Bug, so you can run agents against it safely.

FAQ

Questions about start_test_session

What does the start_test_session tool do? +

Start test mode. Auto-detects dev server, starts a reverse proxy with injected test feedback SDK, and opens the browser. After calling this, follow these steps: 1. Call get_test_history(module) to check past test records 2. Call create_checklist(title, items) to push a structured test plan 3. Tell the user to test. Shortcuts: Alt+E (element report), Alt+S (screenshot), Esc (exit) 4. Call get_checklist_status() and list_feedbacks() to read results 5. Fix issues, call resolve_feedback(id) for each — user verifies in browser 6. Call save_test_record() to persist results 7. Call stop_test_session() when done. It is categorised as a Execute tool in the Yo Bug 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_test_session? +

Register the Yo Bug MCP server in PolicyLayer and add a rule for start_test_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 Yo Bug. Nothing to install.

What risk level is start_test_session? +

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

Can I rate-limit start_test_session? +

Yes. Add a rate_limit block to the start_test_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_test_session completely? +

Set action: deny in the PolicyLayer policy for start_test_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_test_session? +

start_test_session is provided by the Yo Bug MCP server (wyykerwin/yo-bug). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.