AI agents call list_sources to retrieve information from Mcp Newsnow without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool simply lists metadata about available news sources. It retrieves information only; it does not create, modify, delete, execute code, or commit financial transactions. The operation is read-only with no impact on system state or data integrity.
From the tool's definition Tool name 'list_sources' and description '列出所有可用的新闻来源和对应的中文名称' (list all available news sources and their Chinese names) clearly indicates a retrieval operation that enumerates data without modification or side effects.
Documented attack patterns abuse exactly the kind of access list_sources gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Newsnow, and nothing reaches the server without passing your rules. This is the rule we recommend for list_sources:
{
"version": "1",
"default": "deny",
"tools": {
"list_sources": {}
}
}list_sources is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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列出所有可用的新闻来源和对应的中文名称. It is categorised as a Read tool in the Mcp Newsnow MCP Server, which means it retrieves data without modifying state.
Register the Mcp Newsnow MCP server in PolicyLayer and add a rule for list_sources: 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 Mcp Newsnow. Nothing to install.
list_sources 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_sources 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_sources. 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_sources is provided by the Mcp Newsnow MCP server (sligter/mcp_newsnow). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 4 Mcp Newsnow tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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4 Mcp Newsnow tools catalogued and risk-classified — across an index of 42,500+ MCP servers.