tlc_coverage · Tlaplus MCP: Risk & Policy

WHAT IT DOES

What tlc_coverage does on Tlaplus

AI agents invoke tlc_coverage to trigger actions in Tlaplus. 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 tlc_coverage needs a policy

This tool triggers execution of the TLA+ model checker against a specification. While the primary purpose is analysis and verification (not modifying persistent state), it runs arbitrary computational processes whose resource consumption and side effects depend on the specification provided. An agent could supply a pathological spec causing excessive CPU/memory use or long execution times.

From the tool's definition Tool description states 'Run TLC model checker' — TLC is TLA+'s model checker that executes formal specifications to explore state spaces. The tool actively runs verification against a provided specification rather than passively reading or analyzing it.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

tlc_coverage Rate-limited

tlc_coverage 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": {
    "tlc_coverage": {
      "limits": [
        {
          "counter": "tlc_coverage_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 Tlaplus, so you can run agents against it safely.

FAQ

Questions about tlc_coverage

What does the tlc_coverage tool do? +

Run TLC model checker with action coverage reporting. Shows how many times each action was taken and how many distinct states it produced, helping identify under-explored parts of the spec. It is categorised as a Execute tool in the Tlaplus MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on tlc_coverage? +

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

What risk level is tlc_coverage? +

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

Can I rate-limit tlc_coverage? +

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

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

tlc_coverage is provided by the Tlaplus MCP server (richashworth/tlaplus-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.