grant_permissions · PostgreSQL MCP Server MCP: Risk & Policy

WHAT IT DOES

What grant_permissions does on PostgreSQL MCP Server

AI agents use grant_permissions to create or update resources in PostgreSQL MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PostgreSQL MCP Server environment.

WHY IT NEEDS A POLICY

Why grant_permissions needs a policy

Granting permissions modifies access control settings for a user, which is a write operation on the database's security configuration. While reversible (permissions can be revoked), misuse could allow unauthorized users to gain elevated privileges, making the blast radius high. It does not execute code, destroy data, or involve financial transactions.

From the tool's definition Grant permissions to a user

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

grant_permissions Rate-limited

grant_permissions stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "grant_permissions": {
      "limits": [
        {
          "counter": "grant_permissions_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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 MCP Server, so you can run agents against it safely.

FAQ

Questions about grant_permissions

What does the grant_permissions tool do? +

Grant permissions to a user. It is categorised as a Write tool in the PostgreSQL MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on grant_permissions? +

Register the PostgreSQL MCP Server MCP server in PolicyLayer and add a rule for grant_permissions: 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 MCP Server. Nothing to install.

What risk level is grant_permissions? +

grant_permissions is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit grant_permissions? +

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

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

grant_permissions is provided by the PostgreSQL MCP Server MCP server (reckersai/mcpg). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.