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rubenyh

Supabase Read-Only MCP Server

by rubenyh

List Allowed Tables

list_allowed_tables

List all configured and validated tables and views in a read-only Supabase database before describing or selecting them.

Instructions

List only configured and validated tables/views; use before describing or selecting.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
okYes
errorNo
objectsNo
object_countNo

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A4.2/5.0
Behavior3/5

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

With no annotations, the description must carry the behavioral burden. It usefully discloses that only tables passing configuration/validation checks are returned (a permission-scoping trait), but says nothing about whether access is required, error behavior, or whether results are cached. The output schema covers the return shape, offsetting some of the 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?

A single compact sentence with the scope constraint front-loaded and the usage rule trailing as a clear directive. No filler.

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 zero-parameter listing tool with a fully specified output schema, the description covers the essential purpose and sequencing. It stops just short of larger context such as required connection/auth state, but nothing critical to correct invocation is 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?

The tool takes zero parameters, so there is no parameter semantics to document; the baseline of 4 applies.

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?

Names a specific verb (List) and resource (configured/validated tables and views), and the scope qualifier 'only configured and validated' separates it from describe_table and select_rows at a glance.

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?

'use before describing or selecting' explicitly states when to call it and implicitly routes the agent to describe_table/select_rows afterward. It gives a clear sequencing rule but no when-not condition or explicit naming of the sibling tools.

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