AI agents call list_tables 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 performs a straightforward read operation to enumerate database tables. It has no side effects, does not modify data, does not execute code or queries, and does not delete anything. The blast radius is minimal—an AI agent cannot cause harm by invoking this tool, as it only returns informational metadata about database structure.
From the tool's definition Tool name 'list_tables' and description 'データベース内のテーブル一覧を取得' (retrieve list of tables in database) indicate a schema discovery operation that retrieves metadata without modifying or executing queries against data.
Documented attack patterns abuse exactly the kind of access list_tables 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 list_tables:
{
"version": "1",
"default": "deny",
"tools": {
"list_tables": {}
}
}list_tables is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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データベース内のテーブル一覧を取得. 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 list_tables: 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.
list_tables 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 list_tables 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 list_tables. 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.
list_tables 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.