Medium Risk

browser_file_upload

Upload one or multiple files

How to control browser_file_upload ↓

What browser_file_upload does on Playwright MCP with Electron Support

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

Medium Risk

Why browser_file_upload needs a policy

This tool writes data to an external target by uploading files. It is reversible in principle (files can be deleted after upload) and does not execute code or destroy data on its own. However, misuse could exfiltrate sensitive local files or upload malicious content to remote services, making the blast radius high.

From the tool's definition Upload one or multiple files

Documented attack patterns abuse exactly the kind of access browser_file_upload gives an agent:

How to control browser_file_upload

PolicyLayer is an MCP gateway — it sits between your AI agents and Playwright MCP with Electron Support, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_file_upload:

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "browser_file_upload": {
      "limits": [
        {
          "counter": "browser_file_upload_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

browser_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.

  1. Create a free account and register Playwright MCP with Electron Support — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
LIMIT THIS TOOL →

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Related tools and policies

Go deeper

Questions about browser_file_upload

What does the browser_file_upload tool do? +

Upload one or multiple files. It is categorised as a Write tool in the Playwright MCP with Electron Support MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on browser_file_upload? +

Register the Playwright MCP with Electron Support MCP server in PolicyLayer and add a rule for browser_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 Playwright MCP with Electron Support. Nothing to install.

What risk level is browser_file_upload? +

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

Can I rate-limit browser_file_upload? +

Yes. Add a rate_limit block to the browser_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 browser_file_upload completely? +

Set action: deny in the PolicyLayer policy for browser_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 browser_file_upload? +

browser_file_upload is provided by the Playwright MCP with Electron Support MCP server (robertn702/playwright-mcp-electron). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Playwright MCP with Electron Support tool call.

Start from Playwright MCP with Electron Support, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

Free to start. No card required.

34 Playwright MCP with Electron Support tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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