lean_hammer_premise

THE RISK

Low Risk

Why lean_hammer_premise needs a policy

The tool name suggests it may relate to premise selection for the Lean theorem prover's 'hammer' tactic (automated theorem proving), which would be a read/query operation. However, with no description available, confidence is very low. Based on context from sibling tools (LSP interaction, theorem proving), this is likely a read operation that queries or retrieves premises, but cannot be certain.

From the tool's definition Tool name is 'lean_hammer_premise' but description is empty/uninformative.

Documented attack patterns abuse exactly the kind of access lean_hammer_premise gives an agent:

POLICY

How to control lean_hammer_premise

PolicyLayer is an MCP gateway — it sits between your AI agents and Lean Lsp, and nothing reaches the server without passing your rules. This is the rule we recommend for lean_hammer_premise:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "lean_hammer_premise": {
      "limits": [
        {
          "counter": "lean_hammer_premise_rate",
          "window": "minute",
          "max": 60,
          "scope": "grant"
        }
      ]
    }
  }
}

lean_hammer_premise gets a rate cap, and everything else on the server is denied unless you say otherwise.

Create a free account and register Lean Lsp — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

SET A RULE FOR THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Lean Lsp tools

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All 22 Lean Lsp tools →

Other tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Tool risk categories → How PolicyLayer classifies MCP tools by what they can do.
MCP tool → What an MCP tool is and how clients discover and call it.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about lean_hammer_premise

What does the lean_hammer_premise tool do? +

lean_hammer_premise. It is categorised as a Other tool in the Lean Lsp MCP Server, which means it performs auxiliary operations.

How do I enforce a policy on lean_hammer_premise? +

Register the Lean Lsp MCP server in PolicyLayer and add a rule for lean_hammer_premise: 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 Lean Lsp. Nothing to install.

What risk level is lean_hammer_premise? +

lean_hammer_premise is a Other tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit lean_hammer_premise? +

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

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

lean_hammer_premise is provided by the Lean Lsp MCP server (project-numina/lean-lsp-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Lean Lsp tool call.

Start from Lean Lsp, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →