AI agents call list_tables to retrieve information from MCP ClickHouse without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
List operations are fundamentally retrieval queries with no data modification, deletion, or execution of arbitrary code. The absence of a description lowers confidence slightly, but the clear naming convention and context of read-only controls support Read classification. The blast radius if misused is minimal—an attacker could only discover table names and structure.
From the tool's definition Tool name 'list_tables' indicates a query operation that retrieves metadata about tables. The server description emphasizes 'read-only safety controls' for database operations. No parameters or description suggest side effects.
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 MCP ClickHouse, 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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list_tables. It is categorised as a Read tool in the MCP ClickHouse MCP Server, which means it retrieves data without modifying state.
Register the MCP ClickHouse 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 MCP ClickHouse. 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 MCP ClickHouse MCP server (oualib/chmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP ClickHouse, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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55 MCP ClickHouse tools catalogued and risk-classified — across an index of 43,000+ MCP servers.