cache_decr · Amazon MQ MCP Server MCP: Risk & Policy

WHAT IT DOES

What cache_decr does on Amazon MQ MCP Server

AI agents use cache_decr 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_decr needs a policy

Decrementing a counter modifies existing data in the cache. This is a reversible write operation (the counter can be incremented back). The tool modifies state but does not delete data irreversibly, execute code, or involve financial transactions. Severity is medium because misuse could corrupt application state or cause race conditions, but the blast radius is limited to cache values.

From the tool's definition Decrement a counter in the cache

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cache_decr Rate-limited

cache_decr 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_decr": {
      "limits": [
        {
          "counter": "cache_decr_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_decr

What does the cache_decr tool do? +

Decrement a counter in the cache. 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_decr? +

Register the Amazon MQ MCP Server MCP server in PolicyLayer and add a rule for cache_decr: 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_decr? +

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

Can I rate-limit cache_decr? +

Yes. Add a rate_limit block to the cache_decr 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_decr completely? +

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

cache_decr 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.