upload_files · MinIO Storage MCP: Risk & Policy

WHAT IT DOES

What upload_files does on MinIO Storage MCP

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

WHY IT NEEDS A POLICY

Why upload_files needs a policy

Upload operations create or modify data objects in storage, which is reversible (can be deleted via delete_object/delete_objects tools on the same server). The high severity reflects the potential blast radius: an AI agent with unconstrained access could upload large volumes of data, overwrite critical files, or exhaust storage quotas.

From the tool's definition Tool name 'upload_files' and description '批量上传文件' (batch upload files) indicate creation/modification of data in MinIO object storage. This is a Write operation that creates new objects or overwrites existing ones.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

upload_files Rate-limited

upload_files 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_files": {
      "limits": [
        {
          "counter": "upload_files_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 Storage MCP, so you can run agents against it safely.

FAQ

Questions about upload_files

What does the upload_files tool do? +

批量上传文件. It is categorised as a Write tool in the MinIO Storage MCP 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_files? +

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

What risk level is upload_files? +

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

Can I rate-limit upload_files? +

Yes. Add a rate_limit block to the upload_files 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_files completely? +

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

upload_files is provided by the MinIO Storage MCP server (pickstar-2002/minio-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.