上传图片文件用于问卷。支持 png/jpg/gif/jpeg/bmp/webp 格式，文件以 Base64 编码传入，最大约 4MB。
Risk signalsAccepts file system path (file)
Part of the Wjx server.
Free to start. No card required.
AI agents use upload_file to create or modify resources in Wjx. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call upload_file repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Wjx.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"upload_file": {
"limits": [
{
"counter": "upload_file_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Wjx policy for all 58 tools.
These attack patterns abuse exactly the kind of access upload_file gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
上传图片文件用于问卷。支持 png/jpg/gif/jpeg/bmp/webp 格式，文件以 Base64 编码传入，最大约 4MB。. It is categorised as a Write tool in the Wjx MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Wjx MCP server in PolicyLayer and add a rule for upload_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 Wjx. Nothing to install.
upload_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 upload_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 upload_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.
upload_file is provided by the Wjx MCP server (wjx-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 58 Wjx tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.