list_schemas · MCP Data Visualization Server MCP

WHAT IT DOES

What list_schemas does on MCP Data Visualization Server

AI agents call list_schemas to retrieve information from MCP Data Visualization Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

THE RISK

Low Risk

Why list_schemas needs a policy

This tool retrieves metadata about schemas within a Databricks catalog. It is a read-only operation that queries existing data structures without creating, modifying, deleting, or executing operations. The blast radius of misuse is minimal—an attacker gains only visibility into schema names, which is typically low-sensitivity metadata in enterprise data warehouses.

From the tool's definition Tool name 'list_schemas' and description 'List available schemas in a Databricks catalog' indicate a simple query/retrieval operation with no side effects.

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

POLICY

How to control list_schemas

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

policy.json

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

list_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 MCP Data Visualization 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 list_schemas

What does the list_schemas tool do? +

List available schemas in a Databricks catalog. It is categorised as a Read tool in the MCP Data Visualization Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_schemas? +

Register the MCP Data Visualization Server MCP server in PolicyLayer and add a rule for list_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 MCP Data Visualization Server. Nothing to install.

What risk level is list_schemas? +

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

Can I rate-limit list_schemas? +

Yes. Add a rate_limit block to the list_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 list_schemas completely? +

Set action: deny in the PolicyLayer policy for list_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 list_schemas? +

list_schemas is provided by the MCP Data Visualization Server MCP server (xoniks/mcp-visualization-duckdb). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP Data Visualization Server tool call.

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

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28 MCP Data Visualization Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.