file_upload · Brave Browser MCP Server MCP: Risk & Policy

WHAT IT DOES

What file_upload does on Brave Browser MCP Server

AI agents invoke file_upload to trigger actions in Brave Browser MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why file_upload needs a policy

This tool triggers an external operation (file upload) in a browser, sending local files to a remote destination. The effects depend on which files are uploaded and to which endpoint, potentially exfiltrating sensitive local data. It spans Write and Execute categories; Execute is more appropriate given it triggers a browser-mediated operation with variable and potentially irreversible external effects.

From the tool's definition Uploads one or more files to a file input element

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

file_upload Rate-limited

file_upload stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "file_upload": {
      "limits": [
        {
          "counter": "file_upload_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Brave Browser MCP Server, so you can run agents against it safely.

FAQ

Questions about file_upload

What does the file_upload tool do? +

Uploads one or more files to a file input element. It is categorised as a Execute tool in the Brave Browser MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on file_upload? +

Register the Brave Browser 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 Brave Browser MCP Server. Nothing to install.

What risk level is file_upload? +

file_upload is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

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 Brave Browser MCP Server MCP server (slaveofgod1/brave-browser-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.