minio_put_object · MinIO MCP Server MCP: Risk & Policy

WHAT IT DOES

What minio_put_object does on MinIO MCP Server

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

WHY IT NEEDS A POLICY

Why minio_put_object needs a policy

This tool creates new objects or overwrites existing ones in cloud storage. While the operation is reversible (via minio_remove_object), an AI agent could inadvertently upload sensitive data, large files that consume storage quota, or overwrite critical objects. The impact is bounded by storage permissions and quota limits, making it Write rather than Execute or Destructive.

From the tool's definition Tool description states 'Upload content as an object to MinIO bucket'. The action of uploading/putting an object creates or modifies data in the bucket, which is reversible (the object can be deleted via minio_remove_object).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

minio_put_object Rate-limited

minio_put_object 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": {
    "minio_put_object": {
      "limits": [
        {
          "counter": "minio_put_object_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 MinIO MCP Server, so you can run agents against it safely.

FAQ

Questions about minio_put_object

What does the minio_put_object tool do? +

Upload content as an object to MinIO bucket. It is categorised as a Write tool in the MinIO 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 minio_put_object? +

Register the MinIO MCP Server MCP server in PolicyLayer and add a rule for minio_put_object: 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 MinIO MCP Server. Nothing to install.

What risk level is minio_put_object? +

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

Can I rate-limit minio_put_object? +

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

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

minio_put_object is provided by the MinIO MCP Server MCP server (raphaelren/minio-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.