Explains the execution plan for a SQL query, showing how the database will execute it and provides detailed cost estimates.
AI agents call explain_query to retrieve information from Postgres MCP Pro without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool's purpose is to analyze and explain how a query *would* execute, not to execute it or modify any data. It retrieves metadata about query optimization and cost information. This is a safe introspection capability with no side effects, fitting the 'Read' category of retrieving/querying information.
From the tool's definition Tool description states it 'Explains the execution plan for a SQL query' and 'provides detailed cost estimates' — these are read-only operations that retrieve and display query plan metadata without modifying or executing the query against actual data.
Attacks that exploit this kind of access
Explains the execution plan for a SQL query, showing how the database will execute it and provides detailed cost estimates. It is categorised as a Read tool in the Postgres MCP Pro MCP Server, which means it retrieves data without modifying state.
Register the Postgres MCP Pro 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 Postgres MCP Pro. 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 Postgres MCP Pro MCP server (luislopezsanchez/postgres-mcp-server). 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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