AI agents call mysql_query to retrieve information from Mysql without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool is explicitly constrained to read-only queries, meaning it retrieves or queries data without creating, modifying, or deleting any data. Even though the server supports other Write and Destructive operations (create_*, alter_*, drop_*), this specific tool cannot perform those actions. The read-only constraint limits blast radius to information disclosure risks, which is low severity.
From the tool's definition Tool name 'mysql_query' and description 'Execute read-only MySQL queries' explicitly indicate read-only operations with no side effects.
Documented attack patterns abuse exactly the kind of access mysql_query gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mysql, and nothing reaches the server without passing your rules. This is the rule we recommend for mysql_query:
{
"version": "1",
"default": "deny",
"tools": {
"mysql_query": {}
}
}mysql_query is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Execute read-only MySQL queries. It is categorised as a Read tool in the Mysql MCP Server, which means it retrieves data without modifying state.
Register the Mysql MCP server in PolicyLayer and add a rule for mysql_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 Mysql. Nothing to install.
mysql_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 mysql_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 mysql_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.
mysql_query is provided by the Mysql MCP server (mukul975/mysql-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mysql, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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233 Mysql tools catalogued and risk-classified — across an index of 43,000+ MCP servers.