AI agents call detect-languages to retrieve information from Pdf without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool analyzes document content to identify languages present, which is a read-only operation that retrieves information without creating, modifying, deleting, executing code, or committing financial actions. Language detection does not alter the document or trigger external operations based on variable arguments—it simply extracts and reports linguistic metadata.
From the tool's definition Tool performs language detection on PDF documents. The description '检测PDF文档中使用的语言' (detects languages used in PDF documents) indicates a query/analysis operation with no modification or side effects.
Documented attack patterns abuse exactly the kind of access detect-languages gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Pdf, and nothing reaches the server without passing your rules. This is the rule we recommend for detect-languages:
{
"version": "1",
"default": "deny",
"tools": {
"detect-languages": {}
}
}detect-languages is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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检测PDF文档中使用的语言. It is categorised as a Read tool in the Pdf MCP Server, which means it retrieves data without modifying state.
Register the Pdf MCP server in PolicyLayer and add a rule for detect-languages: 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 Pdf. Nothing to install.
detect-languages 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 detect-languages 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 detect-languages. 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.
detect-languages is provided by the Pdf MCP server (saury1120/pdf-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 9 Pdf tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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9 Pdf tools catalogued and risk-classified — across an index of 42,500+ MCP servers.