下载附件，返回 Base64 编码的文件内容。
AI agents call download_file to retrieve information from Agent-Comm-Hub without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and returns file content in Base64 format. It performs a read operation with no side effects—no creation, modification, deletion, or execution of code. The worst-case misuse by an AI agent would be unauthorized data access, which is serious but not as severe as write/execute/destructive categories.
From the tool's definition Tool name 'download_file' and description '下载附件，返回 Base64 编码的文件内容' (Download attachment, return Base64 encoded file content) indicate data retrieval without modification.
Attacks that exploit this kind of access
下载附件，返回 Base64 编码的文件内容。. It is categorised as a Read tool in the Agent-Comm-Hub MCP Server, which means it retrieves data without modifying state.
Register the Agent-Comm-Hub MCP server in PolicyLayer and add a rule for download_file: 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 Agent-Comm-Hub. Nothing to install.
download_file 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_file 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_file. 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_file is provided by the Agent-Comm-Hub MCP server (liuboacean/agent-comm-hub). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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