Get comprehensive table documentation including schema, business context, usage patterns, and data quality insights.
AI agents call explain_table to retrieve information from MCP BigQuery 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 queries metadata and documentation about tables. It performs no writes, deletes, code execution, or financial operations. The action verb 'Get' and the read-only nature of documentation access clearly indicate a Read category classification. Severity is low because metadata queries pose minimal risk even if misused by an AI agent.
From the tool's definition Tool description states 'Get comprehensive table documentation' with scope limited to 'schema, business context, usage patterns, and data quality insights'—all informational retrieval with no modification, deletion, or execution capabilities.
Attacks that exploit this kind of access
Get comprehensive table documentation including schema, business context, usage patterns, and data quality insights. It is categorised as a Read tool in the MCP BigQuery Server MCP Server, which means it retrieves data without modifying state.
Register the MCP BigQuery Server MCP server in PolicyLayer and add a rule for explain_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 MCP BigQuery Server. Nothing to install.
explain_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 explain_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 explain_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.
explain_table is provided by the MCP BigQuery Server MCP server (mousten/mcp-bigquery-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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