client_list

THE RISK

Low Risk

Why client_list needs a policy

This tool queries and returns information about connected clients on a Valkey (Redis-compatible) server. It performs a read-only operation that retrieves state information without modifying, executing code, deleting data, or committing financial transactions. The blast radius of misuse is minimal—an attacker could only discover which clients are connected, which is low-impact information disclosure.

From the tool's definition Tool name 'client_list' and description 'Get a list of connected clients to the Valkey server' indicates a retrieval operation with no side effects.

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

POLICY

How to control client_list

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

policy.json

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

client_list 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 Amazon Redshift 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 →

Free to start. No card required.

EXPLORE

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All 805 Amazon Redshift MCP Server tools →

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Go deeper

Roll out MCP under one policy → Per-person scoped tokens, one central policy, and full audit across every server your team connects.
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 →
PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about client_list

What does the client_list tool do? +

Get a list of connected clients to the Valkey server. It is categorised as a Read tool in the Amazon Redshift MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on client_list? +

Register the Amazon Redshift MCP Server MCP server in PolicyLayer and add a rule for client_list: 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 Amazon Redshift MCP Server. Nothing to install.

What risk level is client_list? +

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

Can I rate-limit client_list? +

Yes. Add a rate_limit block to the client_list 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 client_list completely? +

Set action: deny in the PolicyLayer policy for client_list. 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 client_list? +

client_list is provided by the Amazon Redshift MCP Server MCP server (awslabs.redshift-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Amazon Redshift MCP Server tool call.

Start from Amazon Redshift 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 →