upload_to_s3 · Awslabs Valkey MCP: Risk & Policy

WHAT IT DOES

What upload_to_s3 does on Awslabs Valkey

AI agents use upload_to_s3 to create or update resources in Awslabs Valkey — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Awslabs Valkey environment.

WHY IT NEEDS A POLICY

Why upload_to_s3 needs a policy

Upload to S3 creates or modifies objects in cloud storage, a reversible Write operation. Severity is high because uncontrolled uploads could fill storage, incur costs, or expose sensitive data. Confidence is moderate (0.75) due to the empty description lacking explicit details about scope, authentication, or data handling.

From the tool's definition Tool name 'upload_to_s3' indicates uploading data to Amazon S3 storage. The empty description limits certainty, but upload operations modify cloud storage state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

upload_to_s3 Rate-limited

upload_to_s3 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": {
    "upload_to_s3": {
      "limits": [
        {
          "counter": "upload_to_s3_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 Awslabs Valkey, so you can run agents against it safely.

FAQ

Questions about upload_to_s3

What does the upload_to_s3 tool do? +

upload_to_s3. It is categorised as a Write tool in the Awslabs Valkey MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on upload_to_s3? +

Register the Awslabs Valkey MCP server in PolicyLayer and add a rule for upload_to_s3: 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 Awslabs Valkey. Nothing to install.

What risk level is upload_to_s3? +

upload_to_s3 is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit upload_to_s3? +

Yes. Add a rate_limit block to the upload_to_s3 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 upload_to_s3 completely? +

Set action: deny in the PolicyLayer policy for upload_to_s3. 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 upload_to_s3? +

upload_to_s3 is provided by the Awslabs Valkey MCP server (awslabs.valkey-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.