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by airano-ir
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Hybrid

Supabase: Create policy

supabase_create_policy
Destructive

Create Row Level Security policies on Supabase tables to control which roles can read or modify rows. Define the command, roles, and using/check expressions to enforce per-row access rules.

Instructions

[UNIFIED] Create a Row Level Security (RLS) policy on a 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": {
      "site": "<site>",
      "table": "<table>",
      "name": "<name>",
      "definition": "<definition>"
    },
    "name": "supabase_create_policy"
  }
}

Input Schema

NameRequiredDescriptionDefault
nameYes
siteYes
checkNo
rolesNo
tableYes
schemaNopublic
commandNoALL
definitionYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv3.14.0
  2. Removedv3.13.1
  3. First observedv3.4.0

TDQS

C2.4/5.0
Behavior2/5

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

Annotations already declare this is a destructive, non-idempotent write operation. The description adds only the RLS context and does not explain permission requirements, side effects, whether existing policies can conflict, or how roles and commands affect behavior.

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?

The description is a single front-loaded sentence with no wasted wording. However, it is too terse given the eight-parameter destructive operation it documents.

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

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a destructive tool with eight undocumented parameters and no output schema, the description omits critical context needed to invoke it safely. It identifies the core action but leaves most operational details to inference.

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

Parameters1/5

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

Schema description coverage is 0% across eight parameters. The description only mentions creating a policy 'on a table' and does not explain the meaning or valid values of site, name, definition, check, roles, schema, or command.

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: create a Row Level Security policy on a table. It is clear what the tool does, but it does not differentiate the operation from sibling policy tools such as update or delete policy.

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 explicit guidance on when to use this tool versus updating or deleting a policy. The name implies creation, but prerequisites such as required permissions or RLS being enabled are not mentioned.

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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