add_access_key · Rustfs MCP: Risk & Policy

WHAT IT DOES

What add_access_key does on Rustfs

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

WHY IT NEEDS A POLICY

Why add_access_key needs a policy

The tool creates new access keys (service accounts) for S3-compatible storage, which is a reversible write operation that modifies security infrastructure. While credential creation is sensitive and could enable unauthorized access if misused by an AI agent, it is not destructive (the key can be deleted via delete_access_key) nor financial.

From the tool's definition Tool description states 'Create a scoped access key (service account) for a user', indicating irreversible creation of authentication credentials.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_access_key Rate-limited

add_access_key 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": {
    "add_access_key": {
      "limits": [
        {
          "counter": "add_access_key_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 Rustfs, so you can run agents against it safely.

FAQ

Questions about add_access_key

What does the add_access_key tool do? +

Create a scoped access key (service account) for a user. (Refused read-only.). It is categorised as a Write tool in the Rustfs MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_access_key? +

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

What risk level is add_access_key? +

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

Can I rate-limit add_access_key? +

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

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

add_access_key is provided by the Rustfs MCP server (stackblaze/rustfs-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.