Query data from the database (SELECT only for safety)
AI agents call query_data to retrieve information from MCP PostgreSQL Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool is restricted to SELECT queries, which retrieve data without side effects. Although the sibling tools include destructive operations like 'delete_data' and 'alter_table', this specific tool's constraint to SELECT-only queries places it firmly in the Read category with minimal risk if misused by an AI agent.
From the tool's definition Tool description explicitly states 'SELECT only for safety', and the server is described as 'secure read-only access to PostgreSQL databases'.
Attacks that exploit this kind of access
Query data from the database (SELECT only for safety). It is categorised as a Read tool in the MCP PostgreSQL Server MCP Server, which means it retrieves data without modifying state.
Register the MCP PostgreSQL Server MCP server in PolicyLayer and add a rule for query_data: 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 MCP PostgreSQL Server. Nothing to install.
query_data 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 query_data 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 query_data. 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.
query_data is provided by the MCP PostgreSQL Server MCP server (kristofer84/mcp-postgres). 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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