hll_add · Amazon MQ MCP Server MCP: Risk & Policy

WHAT IT DOES

What hll_add does on Amazon MQ MCP Server

AI agents use hll_add to create or update resources in Amazon MQ MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Amazon MQ MCP Server environment.

WHY IT NEEDS A POLICY

Why hll_add needs a policy

This tool creates or modifies data in a reversible manner (elements can be removed or the HyperLogLog can be cleared), making it a Write operation. The severity is medium because misuse could corrupt or pollute HyperLogLog data structures used for analytics/monitoring, but the impact is typically limited to that specific data structure and is not irreversible.

From the tool's definition Tool name 'hll_add' and description 'Add one element to a HyperLogLog' indicate a data modification operation. HyperLogLog is a probabilistic data structure used for cardinality estimation, and 'add' performs an insertion that modifies its state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

hll_add Rate-limited

hll_add stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "hll_add": {
      "limits": [
        {
          "counter": "hll_add_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Amazon MQ MCP Server, so you can run agents against it safely.

FAQ

Questions about hll_add

What does the hll_add tool do? +

Add one element to a HyperLogLog. It is categorised as a Write tool in the Amazon MQ MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on hll_add? +

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

What risk level is hll_add? +

hll_add is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit hll_add? +

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

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

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