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mcp-postgres-guard

mcp-postgres-guard

by vladshykanov
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Remote

List tables

list_tables
Read-onlyIdempotent

Lists tables the agent can read, with row estimates, to prevent wasteful guessing and rate-limit exhaustion.

Instructions

Lists tables the agent is permitted to read, with row estimates. Start here — guessing table names wastes calls against the rate limit.

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_tables"
  }
}

Input Schema

NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A4.7/5.0
Behavior4/5

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

Annotations already provide readOnlyHint and idempotentHint. Description adds value by stating it returns row estimates and mentioning rate limit context, beyond what annotations convey.

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?

Two concise sentences with no wasted words. Front-loaded with key action and followed by usage guidance. Every sentence earns its place.

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 zero parameters and no output schema, description fully informs the agent: what tool returns, when to use, and why it matters. Sibling tools are distinct and covered.

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?

No parameters exist, so baseline is 4. Description implicitly tells agent no input needed, which adds clarity.

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?

Description uses specific verb 'Lists' and resource 'tables' with additional detail 'the agent is permitted to read, with row estimates'. Clearly distinguishes from siblings like describe_table which describes a specific table.

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

Usage Guidelines5/5

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

Explicitly tells agent to 'Start here' and warns against guessing table names due to rate limits. Provides clear when-to-use guidance and alternatives (guessing is bad).

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

Deploy Server

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