cache_set

Set a value in the cache. Args: key: The key to set value: The value to store expire: Optional expiration time in seconds Returns: Success message or error message

SERVERAWS SOURCE@awslabs/mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity verified Pull the record →

This record as markdown: /tools/aws/cache-set.md

WHAT IT DOES

What cache_set does on AWS

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

RISK

Why cache_set is rated Medium

cache_set creates or modifies data in a cache store. It is reversible (values can be overwritten or expire naturally) and has no permanent destructive effects. However, it carries medium severity because misuse by an AI agent could corrupt application state, poison cache entries that other services rely on, or cause denial of service by filling cache with invalid data.

From the tool's definition Tool description states 'Set a value in the cache' with arguments for key, value, and optional expiration. This is a write operation that modifies cached data.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs cache_set safely

PolicyLayer is an MCP gateway: it sits between your AI agents and AWS, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For cache_set, this is the rule to start with:

cache_set Rate-limited

cache_set 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_set": {
      "limits": [
        {
          "counter": "cache_set_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect AWS, apply this rule, and every cache_set call is checked against it from then on.

FAQ

Questions about cache_set

What does the cache_set tool do? +

Set a value in the cache. Args: key: The key to set value: The value to store expire: Optional expiration time in seconds Returns: Success message or error message. It is categorised as a Write tool in the AWS 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_set? +

Register the AWS MCP server in PolicyLayer and add a rule for cache_set: 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. Nothing to install.

What risk level is cache_set? +

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

Can I rate-limit cache_set? +

Yes. Add a rate_limit block to the cache_set 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_set completely? +

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

cache_set is provided by the AWS MCP server (@awslabs/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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