expert_formal · Musubix MCP: Risk & Policy

WHAT IT DOES

What expert_formal does on Musubix

AI agents invoke expert_formal to trigger actions in Musubix. 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 expert_formal needs a policy

This tool triggers external operations by delegating to a formal verification expert system, executing SMT solver queries (Z3) and theorem proving (Lean 4). It runs external computational processes whose effects depend on the arguments provided, placing it in the Execute category.

From the tool's definition Delegate formal verification to the Formal Verifier expert. Use for generating Hoare logic conditions, Z3/SMT queries, and Lean 4 theorems.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

expert_formal Rate-limited

expert_formal 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": {
    "expert_formal": {
      "limits": [
        {
          "counter": "expert_formal_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 Musubix, so you can run agents against it safely.

FAQ

Questions about expert_formal

What does the expert_formal tool do? +

Delegate formal verification to the Formal Verifier expert. Use for generating Hoare logic conditions, Z3/SMT queries, and Lean 4 theorems. It is categorised as a Execute tool in the Musubix MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on expert_formal? +

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

What risk level is expert_formal? +

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

Can I rate-limit expert_formal? +

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

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

expert_formal is provided by the Musubix MCP server (@nahisaho/musubix-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.