AI agents call list_tables to retrieve information from Gcp 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 BigQuery tables within a dataset. It performs a read-only operation that lists existing resources without creating, modifying, deleting, or executing any code. The blast radius of misuse is minimal—an attacker gains only visibility into table structure and organization, not access to table data itself. Classification as Read is appropriate.
From the tool's definition Tool name 'list_tables' and description 'List BigQuery tables in a dataset' indicate a query/retrieval operation with no data modification or deletion.
Attacks that exploit this kind of access
List BigQuery tables in a dataset. It is categorised as a Read tool in the Gcp MCP Server, which means it retrieves data without modifying state.
Register the Gcp MCP server in PolicyLayer and add a rule for list_tables: 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 Gcp. Nothing to install.
list_tables 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_tables 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_tables. 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_tables is provided by the Gcp MCP server (lokimcpuniverse/gcp-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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