List all functions and procedures in a schema.
AI agents call list_functions 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 retrieves and enumerates database function and procedure metadata without creating, modifying, deleting, executing, or triggering any database operations. It is purely informational and has no side effects. The tool sits in the Read category alongside other schema exploration tools (list_tables, list_views, list_schemas, describe_table).
From the tool's definition Tool name 'list_functions' and description 'List all functions and procedures in a schema' indicate a retrieval/query operation with no data modification or code execution. The verb 'list' is characteristic of Read operations.
Documented attack patterns abuse exactly the kind of access list_functions 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 list_functions:
{
"version": "1",
"default": "deny",
"tools": {
"list_functions": {}
}
}list_functions is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all functions and procedures in a schema. 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 list_functions: 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.
list_functions 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_functions 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_functions. 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_functions 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.