Download PDF for a paper from HAL. Args: paper_id: HAL paper identifier. save_path: Directory to save the PDF (default: './downloads'). Returns: str: Path to downloaded PDF.
AI agents call download_hal to retrieve information from Paper Search MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and downloads publicly available academic papers from HAL (a legitimate open-access repository). It performs a read operation with no side effects on the HAL repository or data integrity. The download action is a standard retrieval operation. While it writes files locally, this is a trivial side effect of the read operation itself, not a data modification operation.
From the tool's definition Tool name 'download_hal' and description 'Download PDF for a paper from HAL' indicate retrieval of existing academic papers. Returns only a file path with no modification of data. Takes a paper_id and optional save_path as arguments.
Documented attack patterns abuse exactly the kind of access download_hal gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Paper Search MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for download_hal:
{
"version": "1",
"default": "deny",
"tools": {
"download_hal": {}
}
}download_hal is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Download PDF for a paper from HAL. Args: paper_id: HAL paper identifier. save_path: Directory to save the PDF (default: './downloads'). Returns: str: Path to downloaded PDF. It is categorised as a Read tool in the Paper Search MCP MCP Server, which means it retrieves data without modifying state.
Register the Paper Search MCP server in PolicyLayer and add a rule for download_hal: 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 Paper Search MCP. Nothing to install.
download_hal 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 download_hal 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 download_hal. 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.
download_hal is provided by the Paper Search MCP server (openags/paper-search-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 63 Paper Search MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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63 Paper Search MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.