cache_replace
Replace a value in the cache only if the key exists. Args: key: The key to replace value: The new value expire: Optional expiration time in seconds Returns: Success message or error message
This record as markdown: /tools/aws/cache-replace.md
What cache_replace does on AWS
AI agents use cache_replace 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_replace is rated Medium
This tool creates or modifies data reversibly by replacing cached values. It does not delete data (hence not Destructive), does not execute arbitrary code (hence not Execute), does not move money (hence not Financial), and does not merely read data (hence not Read).
From the tool's definition Tool modifies cached data via replace operation on an existing key. Description states 'Replace a value in the cache' which is a write/update operation.
Attacks that exploit this kind of access
The rule that runs cache_replace 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_replace, this is the rule to start with:
cache_replace 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_replace call is checked against it from then on.
Questions about cache_replace
Replace a value in the cache only if the key exists. Args: key: The key to replace value: The new value 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_replace: 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_replace 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_replace 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_replace. 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_replace 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.
More on AWS, and thousands of servers like it.
This server
Across the catalogue