List all schemas in the database.
AI agents call list_schemas to retrieve information from PostgreSQL MCP Server 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 database schemas without altering any data or executing arbitrary code. It is a read-only operation that explores the database structure, similar to the sibling tool 'list_tables'. The blast radius of misuse is minimal: an attacker gains only schema visibility, not data access or the ability to modify structures or execute queries.
From the tool's definition Tool name is 'list_schemas' and description states 'List all schemas in the database' — a purely retrieval operation with no modification or execution.
Attacks that exploit this kind of access
List all schemas in the database. It is categorised as a Read tool in the PostgreSQL MCP Server MCP Server, which means it retrieves data without modifying state.
Register the PostgreSQL MCP Server MCP server in PolicyLayer and add a rule for list_schemas: 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 PostgreSQL MCP Server. Nothing to install.
list_schemas 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_schemas 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_schemas. 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_schemas is provided by the PostgreSQL MCP Server MCP server (sebivarga/mcp_psql_home). 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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