lean_declaration_file
AI agents call lean_declaration_file to retrieve information from Lean Lsp without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The name implies reading/fetching a file associated with a Lean declaration. No description is provided to confirm side effects, so confidence is low, but the naming pattern is consistent with a read operation. Severity is low as it appears to only retrieve information.
From the tool's definition Tool name 'lean_declaration_file' suggests retrieving file information about a Lean declaration; description is empty.
Documented attack patterns abuse exactly the kind of access lean_declaration_file gives an agent:
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_declaration_file:
{
"version": "1",
"default": "deny",
"tools": {
"lean_declaration_file": {}
}
}lean_declaration_file is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
lean_declaration_file. It is categorised as a Read tool in the Lean Lsp MCP Server, which means it retrieves data without modifying state.
Register the Lean Lsp MCP server in PolicyLayer and add a rule for lean_declaration_file: 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.
lean_declaration_file is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the lean_declaration_file 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.
Set action: deny in the PolicyLayer policy for lean_declaration_file. 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.
lean_declaration_file 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.
Start from Lean Lsp, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
22 Lean Lsp tools catalogued and risk-classified — across an index of 43,000+ MCP servers.