AI agents call lookup_citation to retrieve information from CourtListener MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool appears to be a lookup/retrieval function that queries the CourtListener database for legal citations. No description is provided, which lowers confidence slightly, but the name and context strongly indicate a read-only search operation with no side effects. The sibling tools and server's stated purpose (searching/accessing legal data) reinforce this classification.
From the tool's definition Tool name 'lookup_citation' in context of CourtListener legal database suggests retrieving citation information.
Documented attack patterns abuse exactly the kind of access lookup_citation gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and CourtListener MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for lookup_citation:
{
"version": "1",
"default": "deny",
"tools": {
"lookup_citation": {}
}
}lookup_citation is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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lookup_citation. It is categorised as a Read tool in the CourtListener MCP Server MCP Server, which means it retrieves data without modifying state.
Register the CourtListener MCP Server MCP server in PolicyLayer and add a rule for lookup_citation: 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 CourtListener MCP Server. Nothing to install.
lookup_citation 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 lookup_citation 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 lookup_citation. 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.
lookup_citation is provided by the CourtListener MCP Server MCP server (travis-prall/court-listener-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from CourtListener MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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18 CourtListener MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.