s3_download_file

Download file from S3 bucket

SERVERNcp SOURCE@portel/ncp

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-portel-dev-ncp/s3-download-file.md

WHAT IT DOES

What s3_download_file does on Ncp

AI agents call s3_download_file to retrieve information from Ncp without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why s3_download_file is rated Low

This tool retrieves data from cloud storage without altering, deleting, or executing anything. It is a read-only operation with minimal blast radius—the worst outcome is exposure of already-stored data that the agent has permission to access.

From the tool's definition Tool name 's3_download_file' and description 'Download file from S3 bucket' indicate a retrieval operation with no data modification or deletion.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs s3_download_file safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Ncp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For s3_download_file, this is the rule to start with:

s3_download_file Allowed

s3_download_file is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "s3_download_file": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Ncp, apply this rule, and every s3_download_file call is checked against it from then on.

FAQ

Questions about s3_download_file

What does the s3_download_file tool do? +

Download file from S3 bucket. It is categorised as a Read tool in the Ncp MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on s3_download_file? +

Register the Ncp MCP server in PolicyLayer and add a rule for s3_download_file: 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 Ncp. Nothing to install.

What risk level is s3_download_file? +

s3_download_file is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit s3_download_file? +

Yes. Add a rate_limit block to the s3_download_file 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 s3_download_file completely? +

Set action: deny in the PolicyLayer policy for s3_download_file. 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 s3_download_file? +

s3_download_file is provided by the Ncp MCP server (@portel/ncp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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