browser_file_upload
A write tool on the Playwright MCP server.
This record as markdown: /tools/hanato238-playwright-mcp/browser-file-upload.md
What browser_file_upload does on Playwright
AI agents use browser_file_upload to create or update resources in Playwright, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Playwright environment.
Why browser_file_upload is rated Medium
File upload is a write operation that creates or modifies data on the remote server being automated. While the description is empty (lowering confidence slightly), the name and server context are clear. This is not destructive (reversible), not financial, but is a write action that could have significant impact if an agent uploads malicious or sensitive files.
From the tool's definition Tool name 'browser_file_upload' indicates uploading files to web forms or pages. Within the context of a browser automation server that 'lets LLMs interact with web pages,' this performs a write/create operation that modifies server state or uploads data.
Attacks that exploit this kind of access
The rule that runs browser_file_upload safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Playwright, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For browser_file_upload, this is the rule to start with:
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.
The button opens the PolicyLayer dashboard: create your workspace, connect Playwright, apply this rule, and every browser_file_upload call is checked against it from then on.
Questions about browser_file_upload
browser_file_upload is a write tool on the Playwright MCP server. It is categorised as a Write tool in the Playwright MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Playwright 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. Nothing to install.
browser_file_upload is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
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.
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.
browser_file_upload is provided by the Playwright MCP server (hanato238/playwright-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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