AI agents call jsonb_stats 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 performs analysis and statistical generation on JSON structures, which is a non-destructive read operation. It retrieves and computes metrics without altering data, executing arbitrary code, or triggering external side effects. No reversible writes, deletions, financial transactions, or command execution are implied.
From the tool's definition Tool name 'jsonb_stats' and description 'Analyze JSON structure and generate statistics' indicate read-only querying and analysis operations with no modification or execution capabilities.
Documented attack patterns abuse exactly the kind of access jsonb_stats 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 jsonb_stats:
{
"version": "1",
"default": "deny",
"tools": {
"jsonb_stats": {}
}
}jsonb_stats is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Analyze JSON structure and generate statistics. 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 jsonb_stats: 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.
jsonb_stats 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 jsonb_stats 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 jsonb_stats. 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.
jsonb_stats 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.