Get value at index from list. Args: key: The name of the key index: The index (0-based, negative indices supported) Returns: Value or error message
AI agents call list_get to retrieve information from AWS without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool performs a simple read operation to retrieve data at a specified index from a list. The arguments (key and index) are straightforward data accessors. There is no capability to modify, delete, or execute external operations. The blast radius of misuse is minimal: an agent could only read values it shouldn't have access to, which is a confidentiality concern but not operationally destructive.
From the tool's definition Tool name is 'list_get' and description states 'Get value at index from list.' This is a retrieval operation with no side effects—it fetches a value from a list without modifying, deleting, or executing anything.
Documented attack patterns abuse exactly the kind of access list_get gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and AWS, and nothing reaches the server without passing your rules. This is the rule we recommend for list_get:
{
"version": "1",
"default": "deny",
"tools": {
"list_get": {}
}
}list_get is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get value at index from list. Args: key: The name of the key index: The index (0-based, negative indices supported) Returns: Value or error message. It is categorised as a Read tool in the AWS MCP Server, which means it retrieves data without modifying state.
Register the AWS MCP server in PolicyLayer and add a rule for list_get: 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.
list_get is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_get 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 list_get. 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.
list_get 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.
Start from AWS, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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300 AWS tools catalogued and risk-classified — across an index of 43,000+ MCP servers.