supabase-mcp-server

Describe table

describe_table

Read-only

Inspect a table's columns, types, nullability, defaults, RLS flag, and RLS policy names and commands to understand its structure and security rules.

Instructions

Columns (name, type, nullability, default), the RLS flag and the names and commands of RLS policies for one table.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "table": "<table>"
    },
    "name": "describe_table"
  }
}

Input Schema

Name	Required	Description	Default
`table`	Yes
`schema`	No		public

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 1, 2026

TDQS

C2.7/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value by naming the returned fields (column name/type/nullability/default, RLS flag, RLS policy names and commands), but it says nothing about behavior for a nonexistent table or an invalid schema name.

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

Conciseness3/5

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

It is short with no wasted words, which is good, but it is an incomplete sentence fragment rather than a front-loaded action statement. Economy here comes at the cost of clarity rather than from it.

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?

With no output schema, the description bears the burden of describing return values, and it does list the major returned sections, which is the strongest part. It still leaves the schema parameter and failure behavior unaddressed for a two-parameter tool.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must carry parameter meaning, and it does not. The 'table' parameter is only obliquely referenced via 'one table', and the optional 'schema' parameter (default 'public') is never mentioned at all, despite being the difference between resolving and failing on qualified names.

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

Purpose3/5

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

The description is a noun phrase with no verb, so it reads as a list of return fields rather than a statement of what the tool does. The scope qualifier 'for one table' does implicitly separate it from list_tables, but the agent has to infer that this is a per-table introspection tool from the enumerated fields.

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 statement of when to use this versus list_tables, whoami, or select_rows. The only usable signal is the phrase 'for one table', which hints at the single-table scope but never explicitly routes the agent away from the listing sibling.

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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