verify_precondition · Musubix MCP: Risk & Policy

WHAT IT DOES

What verify_precondition does on Musubix

AI agents invoke verify_precondition 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 verify_precondition needs a policy

This tool runs an external Z3 SMT solver process to check satisfiability of logical expressions. It involves executing a computational engine with user-supplied inputs, making it an Execute category. The blast radius is medium because misuse could lead to resource exhaustion (complex SMT queries) or be used to probe system logic, but it does not directly modify data or move money.

From the tool's definition 'Verify a precondition expression using Z3 SMT solver' — triggers execution of an external SMT solver (Z3) to evaluate logical expressions

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

verify_precondition Rate-limited

verify_precondition 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": {
    "verify_precondition": {
      "limits": [
        {
          "counter": "verify_precondition_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 verify_precondition

What does the verify_precondition tool do? +

Verify a precondition expression using Z3 SMT solver. Checks if the precondition is satisfiable or unsatisfiable. 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 verify_precondition? +

Register the Musubix MCP server in PolicyLayer and add a rule for verify_precondition: 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 verify_precondition? +

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

Can I rate-limit verify_precondition? +

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

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

verify_precondition 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.