cache_add
Add a value to the cache only if the key doesn't exist. Args: key: The key to add value: The value to store expire: Optional expiration time in seconds Returns: Success message or error message
This record as markdown: /tools/aws/cache-add.md
What cache_add does on AWS
AI agents use cache_add 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.
Why cache_add is rated Medium
The tool creates new cache entries or potentially modifies state in a cache system. While caches are typically ephemeral and less critical than durable data stores, an AI agent could abuse this to inject malicious cached values that affect application behavior, poison caches, or cause denial of service through cache exhaustion.
From the tool's definition Tool description states 'Add a value to the cache' — this creates or modifies data in a cache store. The operation is reversible (values can be updated or deleted later), making it a write operation rather than read or destructive.
Attacks that exploit this kind of access
The rule that runs cache_add 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_add, this is the rule to start with:
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.
The button opens the PolicyLayer dashboard: create your workspace, connect AWS, apply this rule, and every cache_add call is checked against it from then on.
Questions about cache_add
Add a value to the cache only if the key doesn't exist. Args: key: The key to add 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.
Register the AWS 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 AWS. Nothing to install.
cache_add is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
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.
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.
cache_add 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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