pg_stats_descriptive
Calculate descriptive statistics (count, min, max, avg, stddev, variance, sum) for a numeric column. Use groupBy to get statistics per category. Warning: using groupBy on high-cardinality columns will result in large JSON payloads.
This record as markdown: /tools/io-github-neverinfamous-postgres-mcp/pg-stats-descriptive.md
What pg_stats_descriptive does on PostgreSQL MCP Server
AI agents call pg_stats_descriptive to retrieve information from PostgreSQL MCP Server without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why pg_stats_descriptive is rated Low
This tool purely retrieves and aggregates statistical data from a numeric column. It performs read-only analytical operations with no side effects on the database state. The groupBy parameter may produce large payloads but remains a data retrieval operation, not a write, execute, or destructive action.
From the tool's definition Tool calculates and returns descriptive statistics (count, min, max, avg, stddev, variance, sum) for numeric columns with optional grouping. No modification, deletion, or execution of arbitrary code is indicated.
Attacks that exploit this kind of access
The rule that runs pg_stats_descriptive safely
PolicyLayer is an MCP gateway: it sits between your AI agents and PostgreSQL MCP Server, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For pg_stats_descriptive, this is the rule to start with:
pg_stats_descriptive is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect PostgreSQL MCP Server, apply this rule, and every pg_stats_descriptive call is checked against it from then on.
Questions about pg_stats_descriptive
Calculate descriptive statistics (count, min, max, avg, stddev, variance, sum) for a numeric column. Use groupBy to get statistics per category. Warning: using groupBy on high-cardinality columns will result in large JSON payloads. It is categorised as a Read tool in the PostgreSQL MCP Server MCP Server, which means it retrieves data without modifying state.
Register the PostgreSQL MCP Server MCP server in PolicyLayer and add a rule for pg_stats_descriptive: 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 PostgreSQL MCP Server. Nothing to install.
pg_stats_descriptive 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 pg_stats_descriptive 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 pg_stats_descriptive. 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.
pg_stats_descriptive is provided by the PostgreSQL MCP Server MCP server (@neverinfamous/postgres-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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