cache_decr · AWS HealthOmics MCP Server MCP: Risk & Policy

WHAT IT DOES

What cache_decr does on AWS HealthOmics MCP Server

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

WHY IT NEEDS A POLICY

Why cache_decr needs a policy

Decrementing a counter modifies existing data in the cache (a reversible write operation). It changes a numeric value but does not permanently delete data. The tool seems out of place on an AWS HealthOmics server, which slightly lowers confidence, but the description clearly indicates a data modification operation.

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 AWS HealthOmics 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 AWS HealthOmics 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 AWS HealthOmics 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 AWS HealthOmics 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 AWS HealthOmics MCP Server MCP server (awslabs.aws-healthomics-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.