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nayzo

mcp-postgresdb-readonly

by nayzo

list-tables

Discover available tables by listing all tables in a PostgreSQL schema. Specify the environment and optionally the schema name to filter results.

Instructions

List all tables in a schema

Input Schema

NameRequiredDescriptionDefault
envYesEnvironment (staging, test, prod)
schemaNoSchema name (defaults to the environment's configured schema)

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv2.0.0

TDQS

C2.9/5.0
Behavior2/5

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

With no annotations, the description carries the full behavioral burden. 'List' implies a read-only operation, but the description says nothing about permissions, result size limits, pagination, or whether large schemas are truncated.

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

Conciseness4/5

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

A single short sentence, front-loaded with the verb and resource, with no filler. It is efficient, though arguably under-specifies for a tool with an environment parameter.

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

Completeness3/5

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 a fully documented two-parameter schema, one sentence is nearly adequate. The lack of any output/pagination context and no annotations leaves it only minimally complete.

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?

Schema description coverage is 100%, so the schema already documents both the env enum and the schema default behavior. The description only restates 'in a schema' and adds no syntax, format, or default-behavior detail beyond the schema.

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 ('List all tables'), which is clearly distinct from siblings like list-schemas or describe-table. However, it does not explicitly differentiate itself from those siblings or state scope (e.g., whether it includes views).

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

Usage Guidelines2/5

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

There is no when-to-use guidance, no mention of when an agent should call list-tables versus describe-table or query, and no prerequisites. Usage is only implied by the name and description.

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