get_db_schemas

THE RISK

Low Risk

Why get_db_schemas needs a policy

This tool performs schema discovery and enumeration, returning informational metadata (schema names, sizes, table counts). It has no side effects, cannot modify data, and presents minimal risk even if misused by an AI agent. The blast radius is limited to information disclosure of database structure.

From the tool's definition Tool name 'get_db_schemas' and description 'List all database schemas with their sizes and table counts' indicate a read-only operation that retrieves metadata without modifying, deleting, or executing operations.

Documented attack patterns abuse exactly the kind of access get_db_schemas gives an agent:

POLICY

How to control get_db_schemas

PolicyLayer is an MCP gateway — it sits between your AI agents and Supabase MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for get_db_schemas:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_db_schemas": {}
  }
}

get_db_schemas is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Supabase MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

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EXPLORE

Related tools and policies

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about get_db_schemas

What does the get_db_schemas tool do? +

List all database schemas with their sizes and table counts. It is categorised as a Read tool in the Supabase MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on get_db_schemas? +

Register the Supabase MCP Server MCP server in PolicyLayer and add a rule for get_db_schemas: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Supabase MCP Server. Nothing to install.

What risk level is get_db_schemas? +

get_db_schemas is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit get_db_schemas? +

Yes. Add a rate_limit block to the get_db_schemas rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block get_db_schemas completely? +

Set action: deny in the PolicyLayer policy for get_db_schemas. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides get_db_schemas? +

get_db_schemas is provided by the Supabase MCP Server MCP server (deploya-labs/mcp-supabase). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Supabase MCP Server tool call.

Start from Supabase MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →