s3_list_buckets

List S3 buckets

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-list-buckets.md

WHAT IT DOES

What s3_list_buckets does on Ncp

AI agents call s3_list_buckets 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_list_buckets is rated Low

This tool performs a read-only operation to list cloud storage buckets. It has no side effects, creates no data, executes no code, and performs no destructive or financial actions. The blast radius is limited to information disclosure of bucket names/metadata already accessible to the authenticated user.

From the tool's definition Tool name 's3_list_buckets' and description 'List S3 buckets' indicate a query operation that retrieves and enumerates existing S3 buckets without modifying or deleting them.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs s3_list_buckets 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_list_buckets, this is the rule to start with:

s3_list_buckets Allowed

s3_list_buckets 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_list_buckets": {}
  }
}

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_list_buckets call is checked against it from then on.

FAQ

Questions about s3_list_buckets

What does the s3_list_buckets tool do? +

List S3 buckets. 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_list_buckets? +

Register the Ncp MCP server in PolicyLayer and add a rule for s3_list_buckets: 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_list_buckets? +

s3_list_buckets is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit s3_list_buckets? +

Yes. Add a rate_limit block to the s3_list_buckets 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_list_buckets completely? +

Set action: deny in the PolicyLayer policy for s3_list_buckets. 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_list_buckets? +

s3_list_buckets 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.

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