AI agents call list_schema to retrieve information from Db Oauth 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 (table names, structures) for inspection purposes. It has no side effects, modifies no data, and merely exposes metadata. The low severity reflects minimal blast radius—even if misused, an AI agent can only discover what tables exist and their structure, not access or modify actual data (which requires the separate query_database tool).
From the tool's definition Tool name 'list_schema' and description 'List tables or describe a specific table' indicate retrieval of schema metadata without modification.
Attacks that exploit this kind of access
List tables or describe a specific table\. It is categorised as a Read tool in the Db Oauth MCP Server, which means it retrieves data without modifying state.
Register the Db Oauth MCP server in PolicyLayer and add a rule for list_schema: 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 Db Oauth. Nothing to install.
list_schema 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_schema 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_schema. 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_schema is provided by the Db Oauth MCP server (kpconnell/db-oauth-mcp-node). 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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