Calculate correlation between two numeric columns (Pearson or Spearman)
AI agents call stats_correlation to retrieve information from Postgres Mcp Legacy without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and analyzes data (correlation calculation) with no side effects, reversibility concerns, or external state changes. It is a pure statistical read operation on column data. The deprecated server status and sibling tools (analyze_db_health, explain_query) confirm this is part of a monitoring/analytics suite, not a data modification tool.
From the tool's definition Tool 'stats_correlation' calculates correlation between numeric columns using statistical methods (Pearson or Spearman).
Documented attack patterns abuse exactly the kind of access stats_correlation gives an agent:
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_correlation:
{
"version": "1",
"default": "deny",
"tools": {
"stats_correlation": {}
}
}stats_correlation is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Calculate correlation between two numeric columns (Pearson or Spearman). It is categorised as a Read tool in the Postgres Mcp Legacy MCP Server, which means it retrieves data without modifying state.
Register the Postgres Mcp Legacy MCP server in PolicyLayer and add a rule for stats_correlation: 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.
stats_correlation 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 stats_correlation 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 stats_correlation. 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.
stats_correlation 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.
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.
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60 Postgres Mcp Legacy tools catalogued and risk-classified — across an index of 43,000+ MCP servers.