AI agents call 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 and enumerates database names from a PostgreSQL server without modifying, executing, or deleting any data. It is purely informational (Read category). Severity is low because listing databases has minimal blast radius—it reveals schema information but cannot damage data or systems. Confidence is high (0.95) because the description unambiguously describes a read operation.
From the tool's definition The tool description explicitly states it 'List databases' in a PostgreSQL server, which is a query/retrieval operation with no side effects. The requirement to use 'list_servers first' confirms it is a read-only informational operation.
Attacks that exploit this kind of access
List databases in a specific PostgreSQL server. REQUIRES serverName parameter - use list_servers first to get valid server names. Do NOT guess server names. 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 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.
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 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 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.
list_databases is provided by the Postgres MCP server (teja-sudo/postgres-mcp-server). 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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