List all PostgreSQL roles (users) in a cluster.
AI agents call list_postgres_roles to retrieve information from CloudNativePG MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and enumerates existing PostgreSQL roles without creating, modifying, deleting, or executing any operations. It is a read-only query that returns metadata about users in the cluster. The severity is low because listing roles poses minimal risk—it exposes role names but not credentials or sensitive data requiring elevated access.
From the tool's definition Tool name 'list_postgres_roles' and description 'List all PostgreSQL roles (users) in a cluster' indicate a query/retrieval operation with no modification or deletion of data.
Attacks that exploit this kind of access
List all PostgreSQL roles (users) in a cluster. It is categorised as a Read tool in the CloudNativePG MCP Server MCP Server, which means it retrieves data without modifying state.
Register the CloudNativePG MCP Server MCP server in PolicyLayer and add a rule for list_postgres_roles: 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 CloudNativePG MCP Server. Nothing to install.
list_postgres_roles 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 list_postgres_roles 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 list_postgres_roles. 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.
list_postgres_roles is provided by the CloudNativePG MCP Server MCP server (wateim/cnpg-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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