List all databases in the PostgreSQL cluster.
AI agents call PostgreSQL_list_databases to retrieve information from Postgres without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves metadata about existing databases without creating, modifying, deleting, or executing any operations. It is a read-only query operation with minimal blast radius if misused by an AI agent.
From the tool's definition Tool name includes 'list' and description states 'List all databases' — a query operation with no modification or side effects.
Documented attack patterns abuse exactly the kind of access PostgreSQL_list_databases gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Postgres, and nothing reaches the server without passing your rules. This is the rule we recommend for PostgreSQL_list_databases:
{
"version": "1",
"default": "deny",
"tools": {
"PostgreSQL_list_databases": {}
}
}PostgreSQL_list_databases is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all databases in the PostgreSQL cluster. It is categorised as a Read tool in the Postgres MCP Server, which means it retrieves data without modifying state.
Register the Postgres MCP server in PolicyLayer and add a rule for PostgreSQL_list_databases: 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 Postgres. Nothing to install.
PostgreSQL_list_databases 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 PostgreSQL_list_databases 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 PostgreSQL_list_databases. 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.
PostgreSQL_list_databases is provided by the Postgres MCP server (mukul975/postgres-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Postgres, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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239 Postgres tools catalogued and risk-classified — across an index of 43,000+ MCP servers.