Upload files through a file input element
AI agents use uploadFiles to create or update resources in PlayMCP Browser Automation Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PlayMCP Browser Automation Server environment.
File uploading is a Write-category operation as it creates or modifies data (files on a remote server) in a reversible manner. Severity is medium because: (1) the actual impact depends entirely on which file input element is targeted and what server processes the upload, (2) it could potentially introduce malware or malicious content if misused by an agent, but (3) uploaded files are typically manageable/deletable.
From the tool's definition Tool uploads files through a file input element; described as uploading files which creates or modifies data on a target system. The context shows this is part of a browser automation server that can interact with web forms and elements.
Documented attack patterns abuse exactly the kind of access uploadFiles gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and PlayMCP Browser Automation Server, and nothing reaches the server without passing your rules. This is the rule we recommend for uploadFiles:
{
"version": "1",
"default": "deny",
"tools": {
"uploadFiles": {
"limits": [
{
"counter": "uploadfiles_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}uploadFiles 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.
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Upload files through a file input element. It is categorised as a Write tool in the PlayMCP Browser Automation Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the PlayMCP Browser Automation Server MCP server in PolicyLayer and add a rule for uploadFiles: 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 PlayMCP Browser Automation Server. Nothing to install.
uploadFiles 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 uploadFiles 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 uploadFiles. 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.
uploadFiles is provided by the PlayMCP Browser Automation Server MCP server (jomon003/playmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from PlayMCP Browser Automation Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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38 PlayMCP Browser Automation Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.