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 Fluid Postgres without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
EXPLAIN plans are informational reads that retrieve query cost and execution metadata from the database engine. They do not modify data, execute arbitrary operations, or have side effects. This is a safe introspection capability for understanding query performance.
From the tool's definition Tool description states it 'Explains the execution plan for a SQL query, showing how the database will execute it and provides detailed cost estimates.' The verb 'Explains' and 'showing' indicate introspection/analysis only.
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 Fluid Postgres MCP Server, which means it retrieves data without modifying state.
Register the Fluid Postgres 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 Fluid Postgres. 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 Fluid Postgres MCP server (povesma/fluid-postgres-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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