stats_percentiles

THE RISK

Low Risk

Why stats_percentiles needs a policy

This tool retrieves and analyzes existing data using standard statistical methods (percentile calculation and interquartile range outlier detection). No data is created, modified, deleted, or executed.

From the tool's definition Tool description states it 'Calculate percentiles and detect outliers using IQR method' — a statistical analysis operation with no data modification, deletion, or execution of external operations.

Documented attack patterns abuse exactly the kind of access stats_percentiles gives an agent:

POLICY

How to control stats_percentiles

PolicyLayer is an MCP gateway — it sits between your AI agents and Postgres Mcp Legacy, and nothing reaches the server without passing your rules. This is the rule we recommend for stats_percentiles:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "stats_percentiles": {}
  }
}

stats_percentiles is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Postgres Mcp Legacy — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

Read tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about stats_percentiles

What does the stats_percentiles tool do? +

Calculate percentiles and detect outliers using IQR method. It is categorised as a Read tool in the Postgres Mcp Legacy MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on stats_percentiles? +

Register the Postgres Mcp Legacy MCP server in PolicyLayer and add a rule for stats_percentiles: 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 Legacy. Nothing to install.

What risk level is stats_percentiles? +

stats_percentiles is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit stats_percentiles? +

Yes. Add a rate_limit block to the stats_percentiles 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.

How do I block stats_percentiles completely? +

Set action: deny in the PolicyLayer policy for stats_percentiles. 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.

What MCP server provides stats_percentiles? +

stats_percentiles is provided by the Postgres Mcp Legacy MCP server (neverinfamous/postgres-mcp-legacy). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Postgres Mcp Legacy tool call.

Start from Postgres Mcp Legacy, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →