file-upload

THE RISK

Medium Risk

Why file-upload needs a policy

This tool creates new file objects in OpenAI's vector store system, which is a reversible write operation. While it doesn't execute code or delete data, uploading files to a remote AI system could enable prompt injection attacks, training data poisoning, or exposure of sensitive data if misused by an agent.

From the tool's definition Tool description states 'Upload a local file to OpenAI' — this creates/adds new data to a remote service (OpenAI Vector Stores). The name 'file-upload' and description 'upload file' indicates a create/modify operation.

Documented attack patterns abuse exactly the kind of access file-upload gives an agent:

POLICY

How to control file-upload

PolicyLayer is an MCP gateway — it sits between your AI agents and Universal OpenAI Vector Store MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for file-upload:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "file-upload": {
      "limits": [
        {
          "counter": "file-upload_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

file-upload 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.

Create a free account and register Universal OpenAI Vector Store MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Universal OpenAI Vector Store MCP Server tools

Destructive file-delete Permanently delete a file from your OpenAI account. This will remove the file from all vec Destructive vector-store-delete Delete a vector store Destructive vector-store-file-delete Delete a file from a vector store Execute vector-store-file-batch-cancel Cancel a file batch Write upload-create Create a multipart upload session for large files (>25MB). This enables efficient upload o Write vector-store-create Create a new vector store Write vector-store-file-add Add an existing file to a vector store Write vector-store-file-batch-create Create a file batch for a vector store

All 21 Universal OpenAI Vector Store MCP Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about file-upload

What does the file-upload tool do? +

Upload a local file to OpenAI for use with vector stores and assistants. This enables the complete workflow: upload file → add to vector store. It is categorised as a Write tool in the Universal OpenAI Vector Store 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 file-upload? +

Register the Universal OpenAI Vector Store MCP Server MCP server in PolicyLayer and add a rule for file-upload: 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 Universal OpenAI Vector Store MCP Server. Nothing to install.

What risk level is file-upload? +

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

Can I rate-limit file-upload? +

Yes. Add a rate_limit block to the file-upload 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 file-upload completely? +

Set action: deny in the PolicyLayer policy for file-upload. 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 file-upload? +

file-upload is provided by the Universal OpenAI Vector Store MCP Server MCP server (jezweb/openai-vector-assistant-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Universal OpenAI Vector Store MCP Server tool call.

Start from Universal OpenAI Vector Store MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →