Skip to main content
Glama
Sign In
MCPg - Production-grade PostgreSQL MCP Server

MCPg - Production-grade PostgreSQL MCP Server

by devopam
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Hybrid

List roles

list_roles
Read-only

List PostgreSQL database roles and their attributes, such as superuser, login, replication, and connection limits, to audit permissions and manage access.

Instructions

List the database roles and their attributes, excluding PostgreSQL's own roles unless include_system is true. Returns a list of objects with name, superuser, create_role, create_db, can_login, replication, bypass_rls, connection_limit, member_of.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "list_roles"
  }
}

Input Schema

NameRequiredDescriptionDefault
databaseNoOptional: a database id from list_databases, to target a configured secondary (read-only) database; omit for the primary. Database names that are not configured ids are rejected.
include_systemNo

Output Schema

NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv0.8.4
    • changedInput schema / properties / database / description
      Previous value: -"Optional: target a configured secondary (read-only) database by name; omit for the primary. Call list_databases to see the configured ids."New value: +"Optional: a database id from list_databases, to target a configured secondary (read-only) database; omit for the primary. Database names that are not configured ids are rejected."
  2. First observedv0.6.8

TDQS

A3.9/5.0
Behavior4/5

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

Annotations already establish that this is a safe read-only operation with no external side effects. The description adds meaningful behavior beyond that by stating that PostgreSQL's own roles are excluded by default and by naming the returned role attributes. It does not mention ordering, pagination, or permission prerequisites, but those gaps are minor for this simple read tool.

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 tight sentences with the core scope and default filtering front-loaded. Every clause adds useful information, and there is no redundant or empty wording.

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

Completeness4/5

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

For a simple read-only list tool with an output schema and readOnly annotations, the description covers the key behavior and return object shape. It could be slightly more complete by mentioning ordering or pagination limits, but nothing essential for correct invocation appears to be missing.

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

Parameters4/5

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

Schema description coverage is 50%, and the only undocumented parameter is include_system; the description compensates by explaining that it controls whether PostgreSQL's own roles are included. The database parameter is already richly documented in the schema, so its absence from the description is not a material gap.

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

Purpose4/5

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

The description states a specific verb and resource: it lists database roles and their attributes, and it specifies the system-role exclusion behavior. It does not explicitly distinguish itself from nearby role-related siblings such as get_role_ddl or test_rls_for_role, so it stops short of a 5.

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

Usage Guidelines3/5

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

The description explains the include_system toggle, which gives useful usage context for that parameter. However, it does not state when to choose this tool over alternatives or name any sibling tools, leaving broader usage guidance implied.

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

Deploy Server

Other Tools