Downloads a file from a URL directly to the local file system. Ensures the destination folder exists and handles streaming for large files.
AI agents use download_file to create or update resources in Web-curl MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Web-curl MCP Server environment.
This tool writes data from an external URL to the local filesystem. It is a Write operation (creates files locally), but the severity is high because an AI agent could use it to download malicious files, overwrite existing files, or fill up disk space. It doesn't delete data, but it does create/modify filesystem contents in a potentially impactful way.
From the tool's definition Downloads a file from a URL directly to the local file system. Ensures the destination folder exists and handles streaming for large files.
Documented attack patterns abuse exactly the kind of access download_file gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Web-curl MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for download_file:
{
"version": "1",
"default": "deny",
"tools": {
"download_file": {
"limits": [
{
"counter": "download_file_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}download_file 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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Downloads a file from a URL directly to the local file system. Ensures the destination folder exists and handles streaming for large files. It is categorised as a Write tool in the Web-curl MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Web-curl MCP Server MCP server in PolicyLayer and add a rule for download_file: 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 Web-curl MCP Server. Nothing to install.
download_file 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 download_file 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 download_file. 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.
download_file is provided by the Web-curl MCP Server MCP server (rayss868/mcp-web-curl). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Web-curl MCP Server, 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.
7 Web-curl MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.