AI agents call list_tables to retrieve information from Spark SQL without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a metadata query operation that returns information about existing tables. It has no capability to modify, delete, or execute code. The blast radius of misuse is minimal—an agent could only discover table names it may not have known about, which is a read-only information disclosure with low security impact.
From the tool's definition Tool name 'list_tables' and description 'List all tables in a database' indicate a retrieval/query operation with no side effects. It retrieves metadata about tables but does not modify, delete, or execute operations.
Attacks that exploit this kind of access
List all tables in a database. Uses the default database if not specified. It is categorised as a Read tool in the Spark SQL MCP Server, which means it retrieves data without modifying state.
Register the Spark SQL 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 Spark SQL. 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 Spark SQL MCP server (spark-sql-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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