cache_incr · AWS Lambda Tool MCP Server MCP: Risk & Policy

WHAT IT DOES

What cache_incr does on AWS Lambda Tool MCP Server

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

WHY IT NEEDS A POLICY

Why cache_incr needs a policy

Incrementing a counter modifies existing data in the cache (a write operation). It is reversible in principle (the counter can be decremented or reset), so it does not qualify as Destructive. The blast radius is medium because misuse could corrupt counter state used by dependent systems (e.g., rate limiters, usage tracking), but it does not execute code or move money.

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

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cache_incr Rate-limited

cache_incr 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_incr": {
      "limits": [
        {
          "counter": "cache_incr_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 Lambda Tool MCP Server, so you can run agents against it safely.

FAQ

Questions about cache_incr

What does the cache_incr tool do? +

Increment a counter in the cache. It is categorised as a Write tool in the AWS Lambda Tool 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_incr? +

Register the AWS Lambda Tool MCP Server MCP server in PolicyLayer and add a rule for cache_incr: 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 Lambda Tool MCP Server. Nothing to install.

What risk level is cache_incr? +

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

Can I rate-limit cache_incr? +

Yes. Add a rate_limit block to the cache_incr 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_incr completely? +

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

cache_incr is provided by the AWS Lambda Tool MCP Server MCP server (awslabs.lambda-tool-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.