AI agents use upload_asset to create or update resources in SiYuan MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your SiYuan MCP Server environment.
Uploading assets creates new files or resources within SiYuan, which is a reversible write operation. While it modifies the notebook state by adding files, it is not destructive (files can be deleted), not financial, and does not execute arbitrary code.
From the tool's definition Tool name 'upload_asset' and description '上传资源文件' (upload resource file) indicate file creation/addition to the system.
Documented attack patterns abuse exactly the kind of access upload_asset gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and SiYuan MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for upload_asset:
{
"version": "1",
"default": "deny",
"tools": {
"upload_asset": {
"limits": [
{
"counter": "upload_asset_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}upload_asset 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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上传资源文件. It is categorised as a Write tool in the SiYuan MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the SiYuan MCP Server MCP server in PolicyLayer and add a rule for upload_asset: 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 SiYuan MCP Server. Nothing to install.
upload_asset 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_asset 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_asset. 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_asset is provided by the SiYuan MCP Server MCP server (xgq18237/siyuan_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 52 SiYuan MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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52 SiYuan MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.