list_prepend · Amazon SageMaker AI MCP Server MCP

WHAT IT DOES

What list_prepend does on Amazon SageMaker AI MCP Server

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

WHY IT NEEDS A POLICY

Why list_prepend needs a policy

Prepending a value to a list is a data modification action (Write). It is reversible since the value can be removed. However, the description is minimal and the tool appears in a SageMaker AI context where 'list' could refer to various data structures. Confidence is moderate due to the uninformative description.

From the tool's definition 'Prepend value to list' — modifies a list by adding a value to the front, which is a reversible write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

list_prepend Rate-limited

list_prepend 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": {
    "list_prepend": {
      "limits": [
        {
          "counter": "list_prepend_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 Amazon SageMaker AI MCP Server, so you can run agents against it safely.

FAQ

Questions about list_prepend

What does the list_prepend tool do? +

Prepend value to list. It is categorised as a Write tool in the Amazon SageMaker AI 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 list_prepend? +

Register the Amazon SageMaker AI MCP Server MCP server in PolicyLayer and add a rule for list_prepend: 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 Amazon SageMaker AI MCP Server. Nothing to install.

What risk level is list_prepend? +

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

Can I rate-limit list_prepend? +

Yes. Add a rate_limit block to the list_prepend 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 list_prepend completely? +

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

list_prepend is provided by the Amazon SageMaker AI MCP Server MCP server (awslabs.sagemaker-ai-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.