executeSql · Postgresql MCP: Risk & Policy

WHAT IT DOES

What executeSql does on Postgresql

AI agents invoke executeSql to trigger actions in Postgresql. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why executeSql needs a policy

Although the tool explicitly excludes DDL (CREATE, ALTER, DROP), it still permits arbitrary execution of INSERT, UPDATE, and DELETE statements. An AI agent with access to this tool could maliciously or through prompt injection delete entire tables, modify critical data, or corrupt the database.

From the tool's definition Tool description states it 'Execute[s] an arbitrary SQL statement' and explicitly supports 'INSERT, UPDATE, DELETE, and other DML operations.' The word 'arbitrary' combined with DELETE capability indicates the tool can run any DML command with potentially…

Risk signalsAdmin/system-level operation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

executeSql Rate-limited

executeSql 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "executeSql": {
      "limits": [
        {
          "counter": "executesql_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Postgresql, so you can run agents against it safely.

FAQ

Questions about executeSql

What does the executeSql tool do? +

Execute an arbitrary SQL statement that is NOT DDL (no CREATE, ALTER, DROP). Supports SELECT, INSERT, UPDATE, DELETE, and other DML operations. DDL statements require admin privileges. Uses parameterized queries with $1, $2, etc. It is categorised as a Execute tool in the Postgresql MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on executeSql? +

Register the Postgresql MCP server in PolicyLayer and add a rule for executeSql: 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. Nothing to install.

What risk level is executeSql? +

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

Can I rate-limit executeSql? +

Yes. Add a rate_limit block to the executeSql 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 executeSql completely? +

Set action: deny in the PolicyLayer policy for executeSql. 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 executeSql? +

executeSql is provided by the Postgresql MCP server (vnikhilbuddhavarapu/postgresql-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.