Postgres MCP Pro

get_table_sizes

Assess database storage by viewing table, index, and total sizes for any schema. Sort by total, table, or index size to identify space-heavy tables.

Instructions

Show table sizes including indexes and total.

Args:
    schema_name: Schema to analyze (default: "public").
    sort_by: Sort order — "total", "table", or "indexes" (default: "total").
    database_url: Database URL (optional, uses DATABASE_URL from .env if omitted).

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": "get_table_sizes"
  }
}

Input Schema

Name	Required	Default
`sort_by`	No	total
`schema_name`	No	public
`database_url`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.4.2Sep 6, 2026

TDQS

B3.4/5.0

Behavior2/5

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

No annotations are provided, so the description must carry the full burden of disclosure. It does mention the database_url fallback behavior, but it does not state whether the operation is read-only, whether special permissions are needed, or what side effects might occur. For a database-accessing tool, this is a significant gap.

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 a single front-loaded purpose sentence followed by a clean parameter block. There is no redundancy, and every sentence contributes necessary information.

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?

Given no output schema or annotations, the description covers invocation but not the return contract or failure behavior. An agent knows what the tool does and how to pass arguments, but not what the response structure looks like or when to prefer this tool over siblings, leaving a moderate gap.

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

Parameters5/5

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

The schema has zero property descriptions, yet the description's Args section fully documents all three parameters: schema_name with default 'public', sort_by listing valid values 'total', 'table', or 'indexes', and database_url with its optional env fallback. This provides complete invocation semantics beyond the bare 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 opens with 'Show table sizes including indexes and total,' which names a specific verb and resource. It is clear about the tool's scope, though it does not explicitly differentiate from siblings like get_object_details or analyze_index_performance.

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 guidance about when to use this tool versus alternatives such as analyze_index_performance or get_object_details. The description provides no use cases, prerequisites, or exclusions, leaving the agent to infer applicability.

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

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