AI agents call describe_table to retrieve information from Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves database schema information (column definitions, data types, defaults) without side effects. It is purely informational and read-only, making it a Read category tool with low severity. The confidence is high because the description clearly indicates a query/inspection operation.
From the tool's definition Tool description states 'Get the full structure of a table: columns with data types and defaults' — a retrieval operation that queries metadata about table schema without modifying or executing any data.
Attacks that exploit this kind of access
Get the full structure of a table: columns with data types and defaults,. It is categorised as a Read tool in the Server MCP Server, which means it retrieves data without modifying state.
Register the Server MCP server in PolicyLayer and add a rule for describe_table: 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 Server. Nothing to install.
describe_table 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 describe_table 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 describe_table. 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.
describe_table is provided by the Server MCP server (@nest-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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