cache_add · Amazon MQ MCP Server MCP: Risk & Policy

WHAT IT DOES

What cache_add does on Amazon MQ MCP Server

AI agents use cache_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 cache_add needs a policy

This tool creates or modifies data in a cache store in a reversible manner. It is a Write operation because it stores data without side effects beyond the cache mutation itself. Severity is low because the blast radius of accidental cache writes is limited — corrupted cache data can typically be cleared or overwritten without permanent damage.

From the tool's definition The tool description states it will 'Add a value to the cache' — this is a create/modify operation on cached data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cache_add Rate-limited

cache_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": {
    "cache_add": {
      "limits": [
        {
          "counter": "cache_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 cache_add

What does the cache_add tool do? +

Add a value to the cache only if the key doesn't exist. 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 cache_add? +

Register the Amazon MQ MCP Server MCP server in PolicyLayer and add a rule for cache_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 cache_add? +

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

Can I rate-limit cache_add? +

Yes. Add a rate_limit block to the cache_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 cache_add completely? +

Set action: deny in the PolicyLayer policy for cache_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 cache_add? +

cache_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.