AI agents call nar_horse_history to retrieve information from JVLink MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves historical race performance data for horses in NAR (National Association of Racing) regional horse racing. It performs a read-only query operation with no side effects, no code execution, and no data modification. The severity is low because querying historical racing data poses minimal risk even if misused by an AI agent—it cannot alter records, execute commands, or cause financial transactions.
From the tool's definition Tool name 'nar_horse_history' and description '取得' (retrieve/get) indicate data retrieval. The description explicitly states fetching past race records (過去レース戦績を取得) for NAR regional horse racing without any modification, deletion, or execution capability.
Documented attack patterns abuse exactly the kind of access nar_horse_history gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and JVLink MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for nar_horse_history:
{
"version": "1",
"default": "deny",
"tools": {
"nar_horse_history": {}
}
}nar_horse_history 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.
NAR地方競馬の馬の過去レース戦績を取得. It is categorised as a Read tool in the JVLink MCP Server MCP Server, which means it retrieves data without modifying state.
Register the JVLink MCP Server MCP server in PolicyLayer and add a rule for nar_horse_history: 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 JVLink MCP Server. Nothing to install.
nar_horse_history 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 nar_horse_history 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 nar_horse_history. 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.
nar_horse_history is provided by the JVLink MCP Server MCP server (miyamamoto/jvlink-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from JVLink MCP Server, 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.
25 JVLink MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.