AI agents call list_supported_formats to retrieve information from Document Reader MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool retrieves and returns metadata about supported formats—a read-only operation with no side effects. It does not create, modify, delete, or execute anything. The minimal scope (just listing supported formats) and informational nature make this low severity even if misused.
From the tool's definition Tool name is 'list_supported_formats' and description indicates it lists (列出 = list in Chinese) currently supported document formats. This is a pure query operation with no data modification, deletion, or external execution.
Documented attack patterns abuse exactly the kind of access list_supported_formats gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Document Reader MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_supported_formats:
{
"version": "1",
"default": "deny",
"tools": {
"list_supported_formats": {}
}
}list_supported_formats is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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列出当前支持的文档格式. It is categorised as a Read tool in the Document Reader MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Document Reader MCP Server MCP server in PolicyLayer and add a rule for list_supported_formats: 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 Document Reader MCP Server. Nothing to install.
list_supported_formats 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 list_supported_formats 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 list_supported_formats. 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.
list_supported_formats is provided by the Document Reader MCP Server MCP server (qitianfeng/document-reader-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Document Reader MCP 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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6 Document Reader MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.