Run EXPLAIN on a SELECT query to show the execution plan
AI agents call explain_query to retrieve information from Querybridge without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
EXPLAIN queries are intrinsically non-destructive and return only query execution plan information. They cannot insert, update, delete, or execute arbitrary code. The restriction to SELECT queries further constrains the tool to data retrieval operations. While the server supports execute_query (which could be Execute or Destructive), this specific tool is limited to harmless diagnostic output and poses minimal risk.
From the tool's definition Tool description states 'Run EXPLAIN on a SELECT query to show the execution plan' — EXPLAIN is a read-only diagnostic command that retrieves and displays query metadata without modifying data.
Attacks that exploit this kind of access
Run EXPLAIN on a SELECT query to show the execution plan. It is categorised as a Read tool in the Querybridge MCP Server, which means it retrieves data without modifying state.
Register the Querybridge 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 Querybridge. 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 Querybridge MCP server (mahmoudhassanmustafa/querybridge-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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