pg_role_grants
Show privileges and memberships for a PostgreSQL role. Includes role attributes, membership in other roles, and optionally table-level grants.
This record as markdown: /tools/io-github-neverinfamous-postgres-mcp/pg-role-grants.md
What pg_role_grants does on PostgreSQL MCP Server
AI agents call pg_role_grants to retrieve information from PostgreSQL MCP Server without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why pg_role_grants is rated Low
pg_role_grants retrieves and displays existing database metadata (role privileges, memberships, and grants) with no side effects. It is a passive inspection tool, consistent with the Read category (get, fetch, list). The low severity reflects that exposure of this tool allows an AI agent to query permission information, which has minimal blast radius unless combined with other tools to exploit discovered privileges.
From the tool's definition Tool name and description indicate 'Show privileges and memberships' — a retrieval operation that queries role-related metadata without modification. No create, update, delete, or execution actions described.
Attacks that exploit this kind of access
The rule that runs pg_role_grants safely
PolicyLayer is an MCP gateway: it sits between your AI agents and PostgreSQL MCP Server, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For pg_role_grants, this is the rule to start with:
pg_role_grants is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect PostgreSQL MCP Server, apply this rule, and every pg_role_grants call is checked against it from then on.
Questions about pg_role_grants
Show privileges and memberships for a PostgreSQL role. Includes role attributes, membership in other roles, and optionally table-level grants. It is categorised as a Read tool in the PostgreSQL MCP Server MCP Server, which means it retrieves data without modifying state.
Register the PostgreSQL MCP Server MCP server in PolicyLayer and add a rule for pg_role_grants: 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.
pg_role_grants 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 pg_role_grants 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 pg_role_grants. 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.
pg_role_grants is provided by the PostgreSQL MCP Server MCP server (@neverinfamous/postgres-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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