AI agents call list-tables to retrieve information from BigQuery MCP server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only operation to enumerate tables in a BigQuery dataset. It does not modify, delete, or execute any operations—it simply retrieves and presents schema metadata. The sibling tool 'execute-query' would handle actual query execution (which might be Execute or Destructive depending on query content), but this tool is limited to listing.
From the tool's definition Tool name 'list-tables' and description 'Lists all tables in the BigQuery database' indicates a query operation that retrieves metadata without modifying or executing code. It retrieves or lists data with no side effects.
Documented attack patterns abuse exactly the kind of access list-tables gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and BigQuery MCP server, and nothing reaches the server without passing your rules. This is the rule we recommend for list-tables:
{
"version": "1",
"default": "deny",
"tools": {
"list-tables": {}
}
}list-tables is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Lists all tables in the BigQuery database. It is categorised as a Read tool in the BigQuery MCP server MCP Server, which means it retrieves data without modifying state.
Register the BigQuery MCP server 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 BigQuery MCP server. 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 BigQuery MCP server MCP server (lucashild/mcp-server-bigquery). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from BigQuery MCP server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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3 BigQuery MCP server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.