AI agents call auto_number to retrieve information from Kuaidi100 MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool performs a read-only lookup function—it accepts a tracking number and returns a list of possible courier companies. This is a retrieval operation with no side effects, no data modification, no code execution, and no financial implications. It fits the 'Read' category as it simply queries and returns data. The severity is low because even if misused, returning courier company suggestions poses minimal risk.
From the tool's definition Tool name 'auto_number' with description '根据快递单号，返回可能的快递公司列表' (translates to: 'Based on express tracking number, return a list of possible express delivery companies').
Documented attack patterns abuse exactly the kind of access auto_number gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Kuaidi100 MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for auto_number:
{
"version": "1",
"default": "deny",
"tools": {
"auto_number": {}
}
}auto_number is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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根据快递单号，返回可能的快递公司列表. It is categorised as a Read tool in the Kuaidi100 MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Kuaidi100 MCP Server MCP server in PolicyLayer and add a rule for auto_number: 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 Kuaidi100 MCP Server. Nothing to install.
auto_number is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the auto_number 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 auto_number. 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.
auto_number is provided by the Kuaidi100 MCP Server MCP server (kuaidi100-api/kuaidi100-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Kuaidi100 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.
5 Kuaidi100 MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.