AI agents call explain_query to retrieve information from Tdsql without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
EXPLAIN operations in SQL databases retrieve and display query execution plans and optimization metadata—a read-only introspection activity. However, severity is elevated to medium rather than low because: (1) query plans can reveal database schema, indexing strategies, and performance characteristics that inform attack surface mapping; (2) on a Teradata system providing 'full-stack analytics', explain output may…
From the tool's definition Tool name 'explain_query' suggests analysis of SQL query execution plans; sibling tools include 'execute_query' and 'execute_statement', indicating this server provides query execution and inspection capabilities.
Documented attack patterns abuse exactly the kind of access explain_query gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Tdsql, and nothing reaches the server without passing your rules. This is the rule we recommend for explain_query:
{
"version": "1",
"default": "deny",
"tools": {
"explain_query": {}
}
}explain_query is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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explain_query. It is categorised as a Read tool in the Tdsql MCP Server, which means it retrieves data without modifying state.
Register the Tdsql MCP server in PolicyLayer and add a rule for explain_query: 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 Tdsql. Nothing to install.
explain_query 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 explain_query 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 explain_query. 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.
explain_query is provided by the Tdsql MCP server (ksturgeon-td/tdsql-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Tdsql, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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7 Tdsql tools catalogued and risk-classified — across an index of 43,000+ MCP servers.