psql-query

THE RISK

High Risk

Why psql-query needs a policy

This tool executes arbitrary SQL queries against a PostgreSQL database. Depending on the query, this could be a read, write, or destructive action. Since it can execute any SQL (including DROP, DELETE, UPDATE, INSERT), it must be classified at the most severe applicable level.

From the tool's definition 'Executes a PostgreSQL query via psql' — runs arbitrary SQL against a PostgreSQL database

Documented attack patterns abuse exactly the kind of access psql-query gives an agent:

POLICY

How to control psql-query

PolicyLayer is an MCP gateway — it sits between your AI agents and Lint, and nothing reaches the server without passing your rules. This is the rule we recommend for psql-query:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "psql-query": {
      "limits": [
        {
          "counter": "psql-query_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

psql-query stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

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

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

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Go deeper

Govern code and CI agents → Branch allowlists, approval on merges, and rate caps on the build and pipeline tools agents trigger.
High-risk tools in Lint → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →
PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about psql-query

What does the psql-query tool do? +

Executes a PostgreSQL query via psql and returns structured tabular output. It is categorised as a Execute tool in the Lint MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on psql-query? +

Register the Lint MCP server in PolicyLayer and add a rule for psql-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 Lint. Nothing to install.

What risk level is psql-query? +

psql-query is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit psql-query? +

Yes. Add a rate_limit block to the psql-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.

How do I block psql-query completely? +

Set action: deny in the PolicyLayer policy for psql-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.

What MCP server provides psql-query? +

psql-query is provided by the Lint MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Lint tool call.

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

CHECK YOUR STACK →