query_data · MCP SQL Agent MCP: Risk & Policy

WHAT IT DOES

What query_data does on MCP SQL Agent

AI agents invoke query_data to trigger actions in MCP SQL Agent. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why query_data needs a policy

This tool executes arbitrary SQL queries, which can include not just SELECT statements but potentially INSERT, UPDATE, DELETE, or even DROP depending on what 'safely' restricts. The description says 'safely' but does not explicitly limit to read-only queries, and the broader server description mentions 'full schema awareness' and 'conversational language' implying broad SQL execution capabilities.

From the tool's definition "Execute SQL queries safely" — the tool runs SQL queries against a SQLite database, converting natural language to SQL with full schema awareness.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

query_data Rate-limited

query_data stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "query_data": {
      "limits": [
        {
          "counter": "query_data_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches MCP SQL Agent, so you can run agents against it safely.

FAQ

Questions about query_data

What does the query_data tool do? +

Execute SQL queries safely. Use get_schema() first to understand the database structure. It is categorised as a Execute tool in the MCP SQL Agent MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on query_data? +

Register the MCP SQL Agent MCP server in PolicyLayer and add a rule for query_data: 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 SQL Agent. Nothing to install.

What risk level is query_data? +

query_data is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit query_data? +

Yes. Add a rate_limit block to the query_data 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.

How do I block query_data completely? +

Set action: deny in the PolicyLayer policy for query_data. 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.

What MCP server provides query_data? +

query_data is provided by the MCP SQL Agent MCP server (sharansahu/mcp-sql). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.