@yawlabs/postgres-mcp

List functions and procedures

pg_list_functions

Read-onlyIdempotent

List functions, procedures, and aggregates in a PostgreSQL schema. Get name, arguments, return type, kind, and language for each database routine.

Instructions

List functions, procedures, and aggregates in a schema. Returns name, arguments, return type, kind (function/procedure/aggregate/window), and implementation language.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`schema`	No	Schema name (defaults to 'public').	public

Output Schema

TableJSON Schema

Name	Required	Description	Default
`rows`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv0.12.1Sep 4, 2026
- removedOutput schema / properties / rows / items / properties / return_type / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / rows / items / properties / return_type / type
```
Added value: +[
+  "string",
+  "null"
+]
```

Changed2 schema fields changedv0.12.0Aug 28, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "additionalProperties": false,
+  "properties": {
+    "rows": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "arguments": {
+            "description": "Reconstructed argument list; empty string for a zero-argument routine.",
+            "type": "string"
+          },
+          "kind": {
+            "description": "function | procedure | aggregate | window, or the raw prokind.",
+            "type": "string"
+          },
+          "language": {
+            "type": "string"
+          },
+          "name": {
+            "type": "string"
+          },
+          "return_type": {
+            "anyOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Null for procedures, which have no return type."
+          }
+        },
+        "required": [
+          "name",
+          "arguments",
+          "return_type",
+          "kind",
+          "language"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "rows"
+  ],
+  "type": "object"
+}

First observedv0.7.0Jul 29, 2026

TDQS

A4.1/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context about the kind of information returned (e.g., kind and implementation language), which is helpful but does not disclose extra behavioral traits such as permissions, performance, or system catalog filtering.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences with no filler. The core action and target are front-loaded, and the return fields are listed compactly without redundancy. Every sentence contributes useful information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the single optional parameter fully described in the schema, the presence of an output schema, and annotations covering read-only/idempotent behavior, the description is complete. An agent has everything needed to invoke the tool correctly and understand its result shape.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema fully documents the only parameter ('schema') with its default and meaning, so schema coverage is 100%. The description adds no new parameter-level details beyond referring to 'in a schema', matching the baseline for already-documented parameters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('List') with a precise resource ('functions, procedures, and aggregates in a schema') and enumerates the returned attributes. This clearly distinguishes it from sibling list tools like pg_list_tables or pg_list_schemas based on resource type.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description clearly implies when to use it: when information about schema-level functions, procedures, aggregates, or window functions is needed. It does not explicitly name alternatives or exclusions, but the resource-specific wording is enough to guide selection among the many sibling list tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.