Search for columns by name across all tables.
AI agents call search_columns to retrieve information from Postgres without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries database schema metadata to locate columns matching a name pattern. It performs no insertions, updates, deletions, code execution, or external operations. The blast radius of misuse is minimal—an agent could discover column names but cannot access or modify data directly. Classified as Read with low severity.
From the tool's definition Tool name 'search_columns' and description 'Search for columns by name across all tables' indicate data retrieval with no modification. The verb 'search' and 'explore' context (from server description) confirm read-only operation.
Documented attack patterns abuse exactly the kind of access search_columns gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Postgres, and nothing reaches the server without passing your rules. This is the rule we recommend for search_columns:
{
"version": "1",
"default": "deny",
"tools": {
"search_columns": {}
}
}search_columns is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Search for columns by name across all tables. It is categorised as a Read tool in the Postgres MCP Server, which means it retrieves data without modifying state.
Register the Postgres MCP server in PolicyLayer and add a rule for search_columns: 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 Postgres. Nothing to install.
search_columns 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 search_columns 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 search_columns. 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.
search_columns is provided by the Postgres MCP server (javimaligno/postgres_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Postgres, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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14 Postgres tools catalogued and risk-classified — across an index of 43,000+ MCP servers.